Abstract: Concerning on the safety risks caused by electromagnetic interference of patients implanted with high-risk active implantable medical devices in the environment of domestic MUs, this study evaluates and focuses on the requirements of electromagnetic compatibility in domestic and international standards for rail transit vehicles, the main mechanism of risks caused by EMI, the actual measurement of environmental data in MUs and the working performance of various active implantables in the compartment. The test results shows that all kinds of active implantable medical device samples works normally in the CRH2A EMU in China, and there is still a large margin between the measured radiation emission in MU and the limit required by the standards.