Firstly, the Google Brain's development process and research results were reviewed, and the status was analyzed. Secondly, five problems in knowledge service were pointed out ,that is the low utilization of the knowledge, the fragmentation, the qualities , limited learning abilities versus the quick development of knowledge , the lack of new knowledge and so on. Combined with the Google Brain's research results, the AI knowledge service application model was given. Thirdly, the authors looked into the different application levels AI in knowledge service, including improving the utilization rate and accuracy rate, helping to master knowledge involved, satisfying the potential demand and creating new knowledge. At last, the essay demonstrated that AI development is still in the early stage, and enough data is necessary. Besides, the application should be problem-centered.