In order to solve the safety problems of coal chemical gasifier, such as severe corrosion,  weld overlay crack at the manhole due to complex and rigorous operating conditions, a set of "real-time+periodic" health monitoring system was designed and built for a coal chemical enterprise. The deformation, temperature and acoustic emission data of the loss area of the gasifier in real time, monitor and pre-warn the local strain, temperature and active defect data of the quench chamber of the gasifier could be collected. When the gasifier is shut down, phased array ultrasonic and other detection technologies were used to detect the surface crack of the overlaying layer in the quench chamber, and evaluate whether the crack of the overlaying layer expands in the service process. The results show that the system can evaluate the safety of the gasifier through "real-time+periodic" health monitoring, provide data support for the safety level of the equipment, and effectively ensure the healthy operation of the gasifier.