Abstract： A response surface methodology(RSM) model was built to describe the relationship between the shrinkage in the thickness direction of the thinwalled wax part and injection parameters through experiments. The rationality and adequacy of the model were checked via analysis of variation(ANOVA). Besides, a sensitivity analysis for injection parameters on the dimensional shrinkage variation was conducted. Additionally, in order to reduce the shrinkage, the optimal injection conditions were also obtained by calculating the desirability and genetic algorithm(GA) approach.