To address the problems of shrinkage cavity and porosity during the casting process of a certain ship's sea valve, Cu-7Ni-7Al-4Fe-2Mn alloy sea valve casting was used as the research object. A 3D model of the casting was constructed using the 3D mapping software UG, and a bottom pouring system was designed based on the structural characteristics of the sea valve casting. The process of sand casting was simulated by finite element numerical simulation software, the possible locations of shrinkage cavity and porosity were analysed, and the pouring system of sea valve castings was optimized. The influence of factors such as pouring temperature, pouring time, and sand mold preheating temperature on shrinkage cavity and porosity of casting was studied, and the matching casting process parameters were optimized in combination with orthogonal experimental methods. The results indicate that the influence of the process parameters on the shrinkage rate of sea valve casting decreases in the order of pouring time, sand mold preheating temperature, and pouring temperature. The optimized process parameters included a pouring temperature of 1 200 ℃, a pouring time of 30 s, and a sand mold preheating temperature of 35 ℃. By increasing the size of the riser in the parts where casting defects are easily generated, the occurrence of shrinkage cavity and porosity casting defects is effectively reduced.