Abstract: A kind of new application was proposed towards large-scale Question Answer(QA) pairs resource in this paper. Largcscale QA pairs library based on BaiDu ZhiDao platform was constructed and joined to QA system firstly.Then the question with the highest similarity in the library was recommended to the user by similarity calculation. We downloaded 10500 Web pages in the experiments and extracted 4687 QA pairs successfully. Results of experimental applications utilizing TF/IDF of keywords, syntax match of tree kernel function, semantic distance of sentences synthetically were given to illustrate the proposed technique. The application of our experiments obtained accurate rate by 79. 44 %, 81. 67 %and 88. 33% respectively in terms of using 1，2 or 3 methods abovementioned. The experimental resups show that using one more methods synthetically to calculate similarity can acquire more preferable effects.

Key words: Question and answer system, Information extraction, Question recommend, Semantic distance, Tree kernel function