Based on relevant theories and methods such as business process reengineering and procedure analysis, this paper studies the optimization of outpatient process in hospital by taking the gastroenterology department of R hospital in J city as an example. Through field visits and questionnaire surveys, problems in the current service process in the gastroenterology department are found. Based on business process reengineering theory, this paper optimizes the outpatient process, and uses procedure analysis and Flexsim simulation to do the contrastive analysis of out patient process, which verifies the effectiveness of the optimization scheme.