1. An identifying method of hand-written Latin letter, comprising steps of: (a) collecting chirography coordinates of hand-written Latin letter that are inputted in a terminal unit, and storing said chirography coordinates into a predefined structural array in real time; (b) obtaining new chirography coordinate lattice by preprocessing chirography coordinates and chirography coordinates lattice in a matrix format transformed from said chirography coordinates stored in a structural array; (c) Classifying all standard Latin letters in different layers according to characteristics of each Latin letter during the hand writting, to obtain a coarse classification candidate letter aggregation matching with the inputted hand-written Latin letter, wherein step (c) comprises steps of: (c.1) classifying all standard Latin letter into up-down structure coarse classification candidate letter aggregation and non-up-down structure coarse classification candidate letter aggregation, according to whether the hand-written Latin letter is up-down structure or not, wherein the up-down structure coarse classification candidate letter aggregation includes standard Latin letters with inherent up-down structure during the hand-writing and standard Latin letters with up-down structure caused by the hand-writing, and the non-up-down structure coarse classification candidate letter aggregation includes the standard Latin letters without inherent up-down structure; (c.2) classifying the up-down structure coarse classification candidate letter aggregation into transverse stroke coarse classification candidate letter aggregation and non-transverse stroke coarse classification candidate letter aggregation, according to whether the last stroke of the hand-written standard Latin letter is transverse stroke or not, and take these two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter, wherein the transverse stroke coarse classification candidate letter aggregation includes the hand-written standard Latin letters with inherent transverse last stroke and the hand-written standard Latin letters with transverse last stroke caused by the hand writing; the non-transverse stroke coarse classification candidate letter aggregation includes the hand-written standard Latin letters without inherent transverse last stroke; classifying the non-up-down structure coarse classification candidate letter aggregation into the coarse classification candidate letter aggregations with H=1, 2, 3, and 4, according to the transverse cross number H during the hand writing; (c.3) classifying the coarse classification candidate letter aggregation with H=1 into the coarse classification candidate letter aggregations with S=1, 2, 3, and 4, according to the vertical cross number S during the hand writing, and take these four coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with H=2 into the coarse classification candidate letter aggregations with UP=1, 2, and 3, according to the transverse cross number UP in the ⅓ upper portion of the Latin letter during the hand writing, and take the UP=2 and UP=3 coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with H=3 into the coarse classification candidate letter aggregations with Maxs=1, 2, and 3, according to the optimal vertical cross number Maxs during the hand writing, and take the Maxs=2 and Maxs=3 coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with H=4 into the coarse classification candidate letter aggregations with Down=1, 2, and 3, according to the transverse cross number Down in the lower ⅓ portion of the Latin letter during the hand writing, and take the Down=2 and Down=3 coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; (c.4) classifying the coarse classification candidate letter aggregation with UP=1 into the coarse classification candidate letter aggregations with S 1 =1, 2, and 3, according to the vertical cross number S 1 during the hand writing; classifying the coarse classification candidate letter aggregation with Maxs=1 into the coarse classification candidate letter aggregations with first right-up position, first left-down position, first left-down position and first right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with Down=1 into the coarse classification candidate letter aggregations with S 2 =1, 2, and 3, according to the vertical cross number S 2 during the hand writing; (c.5) classifying the coarse classification candidate letter aggregation with S 1 =1 into the coarse classification candidate letter aggregations with second right-up position, second left-down position, second left-down position and second right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with S 1 =2 into the coarse classification candidate letter aggregations with third right-up position, third left-down position, third left-down position and third right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with S 1 =3 into the coarse classification candidate letter aggregations with fourth right-up position, fourth left-down position, fourth left-down position and fourth right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with first left-up position into the coarse classification candidate letter aggregations with first left arch opening and first non-left arch opening, according to whether there is left arch opening during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with first left-down position, first right-up position and first right-down into the coarse classification candidate letter aggregations with second left arch opening and second non-left arch opening, third left arch opening and third non-left arch opening, fourth left arch opening and fourth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with S 2 =1 into the coarse classification candidate letter aggregations with fifth right-up position, fifth left-down position, fifth left-down position and fifth right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with S 2 =2 into the coarse classification candidate letter aggregations with sixth right-up position, sixth left-down position, sixth left-down position and sixth right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; classifying the coarse classification candidate letter aggregation with S 2 =3 into the coarse classification candidate letter aggregations with seventh right-up position, seventh left-down position, seventh left-down position and seventh right-down position, according to the position information of the last new chirography coordinate point of the new chirography coordinate lattice in the standard Latin letter during the hand writing; (c.6) classifying the coarse classification candidate letter aggregation with second left-up position into the coarse classification candidate letter aggregations with fifth left arch opening and fifth non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with second left-down position, second right-up position and second right-down into the coarse classification candidate letter aggregations with sixth left arch opening and sixth non-left arch opening, seventh left arch opening and seventh non-left arch opening, eighth left arch opening and eighth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with third left-up position into the coarse classification candidate letter aggregations with ninth left arch opening and ninth non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with third left-down position, third right-up position and third right-down into the coarse classification candidate letter aggregations with tenth left arch opening and tenth non-left arch opening, eleventh left arch opening and eleventh non-left arch opening, twelfth left arch opening and twelfth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with fourth left-up position into the coarse classification candidate letter aggregations with thirteenth left arch opening and thirteenth non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with fourth left-down position, fourth right-up position and fourth right-down into the coarse classification candidate letter aggregations with fourteenth left arch opening and fourteenth non-left arch opening, fifteenth left arch opening and fifteenth non-left arch opening, sixteenth left arch opening and sixteenth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with fifth left-up position into the coarse classification candidate letter aggregations with seventeenth left arch opening and seventeenth non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with fifth left-down position, fifth right-up position and fifth right-down into the coarse classification candidate letter aggregations with eighteenth left arch opening and eighteenth non-left arch opening, nineteenth left arch opening and nineteenth non-left arch opening, twentieth left arch opening and twentieth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with sixth left-up position into the coarse classification candidate letter aggregations with twenty-first left arch opening and twenty-first non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with sixth left-down position, sixth right-up position and sixth right-down into the coarse classification candidate letter aggregations with twenty-second left arch opening and twenty-second non-left arch opening, twenty-third left arch opening and twenty-third non-left arch opening, twenty-fourth left arch opening and twenty-fourth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; classifying the coarse classification candidate letter aggregation with seventh left-up position into the coarse classification candidate letter aggregations with twenty-fifth left arch opening and twenty-fifth non-left arch opening, according whether there is left arch opening or not during the hand writing, and take the two coarse classification candidate letter aggregations as the coarse classification candidate letter aggregation that matches with the inputted hand-written Latin letter; classifying the coarse classification candidate letter aggregation with seventh left-down position, seventh right-up position and seventh right-down into the coarse classification candidate letter aggregations with twenty-sixth left arch opening and twenty-sixth non-left arch opening, twenty-seventh left arch opening and twenty-seventh non-left arch opening, twenty-eighth left arch opening and twenty-eighth non-left arch opening respectively, according to whether there is left arch opening during the hand writing; (d) according to the local characteristic of the inputted hand-written Latin letter, matching the inputted hand-written Latin letter with the coarse classification candidate letter aggregation of each aggregation obtained in step (c), and obtain the coarse classification candidate letter aggregation matched with the inputted hand-written Latin letter; (e) extracting a freeman chain code of inputted hand-written Latin letter; calculating a matching probability between the freeman chain code of the inputted hand-written Latin letter and the optimal Hidden Markov Model of each standard letter stored in a predetermined letter library and corresponding to each letter stored in the coarse classification candidate letter aggregation matched with the inputted hand-written Latin letter; obtaining an optimized matching probability from each matching probability; determining that the standard letter stored in the predetermined letter library and corresponding to the optimized matching probability as the final identifying result of inputted hand-written Latin letter.