11. The apparatus as recited in claim 9 , wherein the calculating unit comprises: a first calculation module that calculates a distance between a category click distribution of the query and a category click distribution of the published information based on the category click rate of the query and the category click rate of the published information; and a second calculation module that calculates the similarity degree between the query and the published information based on an interval where the distance locates.
11. The apparatus as recited in claim 9 , wherein the calculating unit comprises: a first calculation module that calculates a distance between a category click distribution of the query and a category click distribution of the published information based on the category click rate of the query and the category click rate of the published information; and a second calculation module that calculates the similarity degree between the query and the published information based on an interval where the distance locates. 12. The apparatus as recited in claim 11 , wherein the first calculation module calculates the distance between the category click distribution of the query and the category click distribution of the published information based on the category click rate of the query and the category click rate of the published information by using a following formula: D ⁡ ( Q p , D p ) = ∑ w ⁢ p Q ⁡ ( w ) · log ⁢ ⁢ p Q ⁡ ( w ) p D ⁡ ( w ) wherein: Q p represents the category click distribution of the query; D p represents the category click distribution of the published information; D(Q p , D p ) represents the distance between the category click distribution of the query and the category click distribution of the published information; p Q (w) represents a category click rate of a string formed by core words in the query at a w th category; p D (w) represents a category click rate of a string formed by core words in the published information at the w th category; and w represents a serial number of a corresponding category in a plurality of categories, w=1,2,LM, where M is a number of all categories in the historical statistics information of the category click rates.