Injection molding is widely used to produce a variety of parts, from the smallest component to entire body panels of cars. It has some advantages, including high production rates, repeatable high tolerances, ability to use a wide range of materials, low labour cost and minimal scrap loss. As a case, the paper introduced the application of MoldFlow software in injection molding development of the mobile telephone frame. Best gate location was obtained. The numerical simulation provided scientific and valuable injection process information. At last, a multi-cavity injection mold for mobile telephone frame was designed, and the NC machining of the mold core was programmed by UG NX software.