Abstract: Aluminum alloy covers have complex appearance, high comprehensive performance and quality requirements.The gravity casting molding of the aluminum alloy cover was simulated and analyzed based on ProCAST software, the aluminum alloy cover structure and gravity casting molding parameters were optimized, and the castings before and after optimization was compared. The results show that the aluminum alloy cover casting has a large body shrinkage rate, and the risers are needed for feeding and the castings need heat treatment.The gravity casting of the aluminum alloy cover has a large number of shrinkage holes and porosity, and poor solidification characteristics at the strengthen reinforcement junction.Optimized aluminum alloy cover structure and gravity casting parameters can improve the wall thickness and shrinkage hole and porosity of castings.