In order to achieve higher speed and better efficiency of the plastic buckle molding, Imageware, the reverse design software, was adopted in this paper to process the point cloud data of the plastic buckle, mesh feature lines and reconstruct the surface,and then the reconstructed plastic buckle model was imported into UG and saved in STL format with the powerful surface repair function of UG to suture discontinuous surfaces. Mold Wizards of UG, the mold design module, was used to create mold assembly model, design parting surface, generate three-dimensional solid model of molding parts according to STL format saved previously and eventually the injection-molded plastic buckle was analyzed with Moldflow / MPI. As was indicated, the optimized design parameters tally with the experimental results basically.