The ability of metal plastic forming and the mechanism performance of the part are correlated with grain granularity of the metal. Grain growth is a prominent character of the microstructure evolution. It is very helpful for the design of process and die structure to study the mechanism of superpalstic deformation and microstructure evolution of superplastic forming. The microstructure evolution of material is impact directly the mechanic performance of the component in superplastic forming. It is necessary to optimize the complex process and to predict the microstructure evolution. A new simulation method that integration the finite element simulation and the microstructure simulation of superplastic forming is introduced in this paper. Monte Catlo method is an odds simulating technique and can simulate time course of microstructure evolution. Based on the studies of superplastic grain growth mechanism, the superplastic grain growth rate equation are derived in this paper by coupling static state anneal grain growth mechanism and deformation stimulated grain growth mechanism. The grain growth drive force of superplastic deformation includes mostly boundary energy and distortion energy. A new drive force model is derived based on energy model. The microstructure evolution is correlated with the stress and strain of the part, and the integration of superplastic forming FE simulation and microstructure evolution MC simulation is realized. Using the integrating simulation technique can predict not only the forming process but also presenting grain growth image of the part. Experimental studies of the part in forming process and microstructure evolution were performed.