Abstract: Due to the fact that only the strain and displacement information of the structure are monitored during the pressure-tight test, it is almost impossible to discover the structural damage of pressure-bearing structures in real time, let alone identify and predict the risk of structural failures. An online scheme for monitoring the safety status of sealed pressure-bearing structures in pressure-tight tests was designed based on the ultrasonic guided wave defect monitoring method. In addition, a monitoring system for test verification was built. The results show that the scheme using high-frequency hybrid sound field dynamic sensing technology has solved the problems involving difficulties to monitor the safety status and to locate the abnormal conditions timely and effectively in large and complex pressure-bearing structures. The effective real-time monitoring and timely warning for the safety of pressure-tight test are achieved. It may provide an effective safety technical guarantee for the development of large spacecraft sealed pressure-bearing structures.