Abstract: Excavating tunnel under existing passenger transferring subway station is of very importance. Stringent risk assessment and control must be applied to keep operation of the subway station safely. The paper mainly introduces the risk assessment and the third-party monitoring measurement of a new tunnel construction underneath a Beijing Subway Wanshou Road Station. This station is a passenger transferring subway station. The tunnel construction might result the settlement of the subway station structure and make the rail distort. It might impact the safety of station operation. The project used methods of structure measuring, construction numerical simulation and the third-party monitoring measurement. The results show that the station was safe and was operated safely. The results presented in the paper may give a good reference to other similar projects.