Abstract: In the traditional investment casting production process of a 304 stainless steel ball valve, the process parameters determined by experience often cannot completely eliminate defects, some shrinkage holes appear at the corners of the valve body and the flange, which seriously affects the product quality.Simulation and defect analysis of the stainless steel round ball valve casting were performed by using ProCAST software, it is found that there are many large and concentrated shrinkage porosity at the corners of the valve body and flange by the traditional process method. The structure of the gating system was redesigned, the process parameters were adjusted, and the orthogonal test scheme was designed.The results show that under the process parameters of pouring temperature of 1550℃, pouring speed of 1.0 kg/s and shell preheating temperature of 1150℃, shrinkage holes at the corners of valve body and flange are eliminated.