Plastic products have widely applied in national defense construction, industrial & agricultural production and daily living. Plastic products manufacturing cannot be separated design and manufacturing of injection mold. By analyzing and comparing the battery cover injection mold and molding process, This paper makes use of MOLDWIZARD module of Unigraphics NX 's, which is the most popular 3D CAD / CAM system standard currently, and has completed the battery cover’s design of the injection mold, which including the number of Cavity volume injection, determination of the layout, selection of injection machine, design of gating system, selection of templates and standard parts, design of stripping and core-pulling mechanism, design calculation of forming part, etc. Check all the parameters of injection machine according to the requirements of Housing parts injection mold. Draw a mold assembly drawings and parts drawing ultimately.