Abstract: Considering that an underwater shield tunnel with defects or affected by a disaster may result in heavy economic losses and harmful social impacts during operation due to complex geological conditions and the environments outside and inside the tunnel, and using the Nanjing Weisan Road river-crossing project as an example, this paper systematically discusses the composition of a health monitoring system. Included in this discussion are the following topics: the selection of monitoring items, the typical section, the acquisition and transmission system of the monitoring data, the central database subsystem, the safety pre-warning and comprehensive evaluation subsystems, and the software system for the user interface. The results show that the health monitoring system, integrated with sensor testing, computer techniques, remote intelligent control, damage detection, signal analysis and safety evaluations, has the advantages of advancement, rationality, practicability, compatibility and convenience.