The large deformation of powder molding pressing machine in the load affects the accuracy of the machine. The model of powder molding press was simplified by finite element method. ANSYS software was employed to simulate the location of the frame deformation in load, deformation and stress distribution of the real case. The sizes and structures of the powder molding pressing frame were changed, such as adding stiffeners on the both sides of the frame support shelf to improve the support plate bending rigidity and resistance to flex capacity. The results showed that the increasing thickness of the steel plate can reduce stress concentration. The overall deformation reduced from the original 0.361688mm to 0.254033mm. The maximum deformation area transferred from the support rack of the frame to the edge of mold shelf. The deformation of Y direction is reduced from 0.336271mm to 0.186853mm. The optimized deformation of the rack and the mold shelf significantly is reduced.