In order to get high quality forgings, it is significant to predict the microstructure evolution during hot forging process accurately. In this study, a simulation model is built by combining FEM with the dynamic recrystallization model of 42CrMo, and the finite element model is proved to be reliable by a serial of upsetting deformation experiment. Then the distributions of microstructure evolution are obtained on upsetting process. Upsetting is beneficial to refine the grain size and drawing can make the distribution of grain size homogeneous. By comparing the simulation results with experiments, the distributions of microstructure are a close match in the middle part of steering arm. The forgings formed by this process have a good microstructure and have high comprehensive mechanical properties.