The quenching process is a complex process, which involves quenching medium flow field, work piece temperature and stress field. In this paper, the 40Cr steel belt wheel is chosen for the sample of finite element method to simulate the quenching process. The temperature changes with time at any position in the work piece are directly reflected in the actual quenching process. The cooling curves of center and general surface are obtained after simulation. Combined with cooling curve of transformation of under cooled austenite, it is easy to predict whether the technological results meet the performance of organization, and conduct a security assessment of the work piece.