A grid portal is one of the most important ways to access grid systems. The disadvantages existing in current grid portals are that they are designed for specific applications, difficult to add new applications. Besides, the security issues are not considered fully in these portals. In this paper, we proposed a user-centric and secure grid portal architecture-USGPA based on portlet. In USGPA, a security portlet model is proposed in which security issues for sensitive data and the portal server are solved. Based on the model, the application portlet model is proposed with which new applications can be encapsulated into portal quickly. Then all portlets for high-performance computing-HPC are designed based on these two models. With these portlets, users can not only manage jobs via portal but also can custom the portal by selecting and managing the applications they required. Last but important, a prototype is implemented to evaluate the scalability, security and efficiency of the architecture.