In this paper, the personalized service on the basis of lack of semantic and the strengths and weaknesses of the existing user model update mechanism, combined with keyword-based user interest ontology semantic information-rich features, design a classification knowledge base, combined with keywords and user interest ontology concept representation. The model of the user s interest is divided into short-term interests and long-term interest, and the two interested in using different establishment and update mechanism. By constantly updating and optimization model, the model can accurately reflect the characteristics of the user s interest. Finally, the effectiveness of the method is verified by experiments, experiments show that the model can improve the performance of user interest modeling.