Abstract: Creep characteristics,physics mechanics and advantage of Xiyuan model and modified Xiyuan model are described briefly.According to the mechanics characteristic of accelerating creep phase,the Xiyuan model is unreasonable to describe the accelerating phase.With the damage variable,the creep strain of damaged materials and undamaged one consists of total strain;furthermore,creep equation of unstable phase is developed.Creep ele-ment equation is founded by finite element method,and the FE program is compiled to analyze creep.