Warpage is a serious defect for the injection-molded parts. In this work, an effective optimization method based on Kriging method is proposed to minimize the warpage in injection molding. Kriging method can build the approximate mapping relationship among warpage and the some process parameters, replacing the FE analysis of warpage that is time consuming in the optimization. Moldflow Plastic Insight software is used to analyze the warpage deformations of trial samples for the injection-molded parts. Applied to a cellular phone, this optimization method effectively decreases the warpage deformation, process parameters such as mold temperature, melt temperature, injection time and packing pressure regarded as design variables of optimization. After results analysis, injection time has most important influence on warpage in the chosen range.