For the folding and pinching defects that were prone to occur on the surface and columns of a certain type of precision hot-die forging engineering machinery planetary carrier forgings, the distributions of billet temperature, metal flow, equivalent stress and equivalent strain during the main forming processes were analyzed by Deform-3D numerical simulation technology, and combined with the practical production, it was found that the large metal flow velocity difference and temperature difference when forming the column were the main reasons for the folding and pinching defects of the forgings. Furthermore, when the metal flowing into the column cavity converges, the larger flow velocity difference can lead to the convergence of larger and smaller flow velocities and the flipping of metals with small flow velocity, which forms folding defect. When the local temperature difference of column is larger and the surface temperature is too high, the plasticity of material changes to make it easy to mix the oxide scale, release agent and other impurities into the material, resulting in the local material being difficult to integrate into the main body of billet, and being separated and converged during the high-speed forming process, which forms the surface pinching of column. Though optimizing the die structure to control the metal flow direction and adjusting the process parameters to control the forging speed and billet sizes, the occurrence of forming defects could be avoided or suppressed effectively, so as to solve the folding and pinching defects of precision hot-die forgings. The trial production results show that the optimized forming process effectively improves the product qualification rate and meets the forming quality requirements.