Deformation of castings during the solidification process puzzles many engineers and scientists for many years.Numerical simulation is a powerful assistant tool to help attain the goal of near-net forming by casting.The traditional methods compute the thermal stress of both the casting and the mold.It suffers the problem of massive calculation and failure of convergence.This paper proposed an improved Mold Surface Element Method,in which the main idea is using the surface elements instead of body elements to express the interactions between the casting and the mold.The present method shows great computation efficiency and provides satisfied precision for engineering.Two practical casting products were used to verify the proposed method.The results observed in practical products agree well with the simulation results.The method is believed to benefit the production practice and provide theoretical guidance.