Abstract: Based on material characteristics, structural features and service requirements of ZL104 swivel base castings, an open top-gating system was preliminarily designed in this paper, and numerical simulation and analysis of the sand casting process were carried out. According to the simulation results of shrinkage cavity and porosity defects generated during mold filling and solidification, the sand casting process of the swivel base castings was improved by adding risers and chills. The optimized casting process simulation results show that the shrinkage defects are effectively controlled, and the final process yield reaches 74.1%.