Abstract: This paper described a regression testing approach based on a Critical Path Selection for composite service, by parsing BPMN execution flow, identified the affected execution flow, selected the appropriate path for regression testing, and generated the regression testing cases. Based on this method, designed and implemented the SOArTester4RT tool, which is based on the SoarOArWare. Experiments demonstrated that SOArTester4RT can parse the BPMN, generate test cases, efficient improved the efficiency of regression testing for composite service evolution.