Much progress has achieved in forging technology, and it has become a popular process for preparation of intricate parts. As a case, a finite element model of the square block forging process was established by DEFORM software. The deformation, distribution and development trend of velocity, mean stress, equivalent strain and equivalent strain rate were predicted. The load-time variation curves in X, Y and Z direction were obtained too. Based on the numerical simulation result, we had a better understanding of the forging process.