Aiming at the accidental abnormal operation of Beidou in an underwater vehicle, an independent real-time monitoring system of Beidou status is designed, which continuously measures and calculates the relevant parameters of the current Beidou status of the vehicle, and carries out temporary intervention control according to the relevant judgment criteria, so as to improve the efficiency of Beidou communication and positioning, so as to improve the navigation performance of the vehicle Safety and reliability. In the design of the system, the internal structure and working environment of the vehicle are fully considered. On the basis of considering the original bus protocol, control conditions and control flow and other related requirements, the commonly used large-size and high-power components such as isolation and switch are abandoned, and the small-size and low-power integrated design scheme is adopted to realize the real-time monitoring function of the Beidou state of an underwater vehicle. The monitoring system has passed the environmental test and electromagnetic compatibility test, and carried a certain type of underwater vehicle in a domestic water area to complete the actual navigation test. The test results show that the monitoring system can intervene in the control when the Beidou of the vehicle is abnormal, and improve the navigation safety and reliability of the vehicle.