Abstract: Void defect in ingot is a typical casting defect. This defect must be eliminated by reasonable forging process to realize the closure of the void, so as to ensure the high quality of forging products. Through numerical simulation and theoretical analysis, the influence of different upsetting processes on the void closing behavior was studied. Using Deform-3D finite element software and numerical simulation method, based on a void evolution model, the influence of friction factor and height-diameter ratio of ingot on the evolution behavior of void defects in ingot during upsetting deformation were analyzed. It was found that the higher the friction factor between ingot and anvil, the closer the height-diameter ratio of ingot is to 1.0, the void in the core position is easier to close, but the void in the contact position between anvil and ingot is more difficult to close.