3. The method according to claim 2 , wherein before extracting the main body text from the information of the source file, the method further comprises: filtering the source file information to keep a partitionable type tag and the information in the kept tag.
4. The method according to claim 3 , wherein the step (2) further comprises: (a) dividing the filtered source file information into text blocks based on the partitionable type tags, and storing contents of all the text blocks as well as distance between each block and its next adjacent text block; (b) choosing the text block with most characters as a base text block; (c) determining a upper limit block and a lower limit block via a relationship between a pre-set threshold and a distance ratio of characters number in the above and below text blocks to the base text block, wherein contents between the upper limit block and the lower limit block are taken as a main body text.