In this paper, Taguchi experimental design method is applied, and injection molding CAE simulation analysis is conducted. Influence factors of warpage of products are analyzed. According to the results of ranking, influence factors of warpag are the packing pressure, packing time, melt temperature and mold temperature. The packing pressure is the most important influence factor. To get the best level combination of various factors, mixed level orthogonal experimental design is applied to the optimization. Optimal levels of combination process parameters are obtained and the quality of injection products is greatly improved.