In this article, a three-dimensional finite element analysis using Deform 3D software has been employed to investigate the plastic deformation behavior during forging of X20CrMoV121 steel. The focus was on the influence of forging temperature on the strain, stress and particle flow velocity distribution during the forging process. From the results, it has been shown that the forging process results in inhomogeneous plastic deformation, hence inhomogeneous strain, stress, and particle flow velocity distribution. As the temperature increased from 800 to 1100 °C, the forging loads and the deformation resistance were observed to decrease with an increase. For each temperature, the load increased rapidly with the stroke and then the increase slowed. This behavior was related to the coefficient of friction at the tool sample interface. It was also shown that the maximum effective stress/strain decreased as the forging temperature increased to 1100 °C. It is suggested that 3D finite element simulation by Deform® 3D software is an efficient method for predicting metal flow behavior during the forging process.