As an important indicator of performance testing in Web applications - load capability is a key factor in determining the performance of Web applications, building load test model is an important prerequisite to obtain load capability of Web application. Based on the user group model and further analysis of the general actual user behavior, this paper increases the parameter personalization function in the user group model. The practical application shows that the improved model can simulate the real user behavior more realistically, and can make the data more statistically significant, so that the performance of web applications can be more accurately predicted.