In the plastic injection molding process, the design of the cooling system plays a key role in the molding quality, molding cycle and production efficiency of the product. In this paper, computer technology is used to perform numerical simulation analysis on the injection mold of the automobile hubcaps. The mold temperature, the ejection temperature time of the plastic part and the distribution of the warpage of the plastic part are used as performance indicators to obtain the deficiencies of the cooling system design. Practice has proved that the cooling system optimization method is reliable and effective, and has certain reference value for the design of injection mold structure.