In order to analyze and optimize the structure of stamping mold, a new load mapping method was proposed for the precise calculation of the load acting on the mold surface. The new method established an accurate load mapping model between the forming force on the triangular element of the deformed sheet metal and the load on the tetrahedron element of the stamping mold after accurately setting a new mapping direction and positioning the different elements. Then the load distribution on the surface of the mold was obtained. A case study applied the loads obtained to a stamping mold design and analysis, and a topology optimization was performed by using the software OptiStruct. Compared with traditional designs, the optimized mold structure can improve the stiffness and strength of the forming mold significantly, and reduce mold weight dramatically. It shows that the method established is feasible and can also be applied to other parts of the stamping mold.