The study aimed at improving the problems of warpage occurring in the mold injection of battery lower cases. Firstly, the effects of variations of molding parameters are investigated in order to minimize the warpage. Secondly, Moldflow software is employed to simulate the molten plastic flow inside the cavity, and followed by the holding pressure analysis. Moreover, Taguchi method is applied to find the optimum distribution of mold temperature, and its results are used to design cooling tubes. Finally, different cooling systems are parametrically simulated and the optimum combinations will be found. The analytical results indicate that the optimum parameters can reduce the warpage problem occurring during mold injection. Therefore, the yield rate of the products can be effectively raised.