<p>Optimization of plastic injection molding(PIM) process parameters was carried out to reduce shrinkage and warpage affecting the quality of plastic injection molding products. There are two factors affecting the quality of injection molding products, including the design parameters of mold and the process parameters, where the most important factor is the process parameters. The process parameters in PIM include injection pressure, injection rate, melt temperature, mold temperature, packing pressure and packing time. The shrinkage and warpage that affect product quality are related with the process parameters. Hence, in order to determine the process parameters for warpage minimization, Moldflow simulation analysis based on the L₂₅ 5-level Taguchi orthogonal design was performed in this paper. Injection rate, melt temperature, mold temperature, packing pressure and packing time were set as process parameters. As the optimization simulation results show, the volumetric shrinkage was 5.6%, the warpage in <i>Y</i> direction was 1.093 3&#xa0;mm, and 61.2% (1.78&#xa0;mm) of warpage was reduced compared to the previous optimization according to the verification test results. Through the optimization process, it can be seen that the most influential factors on the shrinkage and warpage of injection molding product are melt temperature and packing pressure.</p>