With the rapid development of internet technology, focusing on the product design of individual users, emphasizing the interaction design for Web and improving the user experience have become an inevitable trend of Web design, and also the hot spot of the design of personalized search engine. This paper proposed an optimized algorithm for building user models for product design websites. In order to show the design dimensions of Web pages presented by a browser, a concept of freshness is presented in this algorithm. By analyzing the user behavior of browsing Web pages, the model was updated using methods of machine learning. At last, the performance and effectiveness of this algorithm was analyzed and estimated through the simulation experiment.