The invention provides a safety monitoring system for a sewage manhole cover. The system comprises a server, a gateway and a sewage manhole cover safety monitoring subsystem. The gateway comprises a central processing unit, a LoRa communication module, a power module and a network module. The sewage manhole cover safety monitoring subsystem comprises a control module, a power supply module, a LoRamodule, a GPS positioning module disposed on the sewage manhole cover, a water level monitoring module disposed on the sewage manhole, an inclination angle monitoring module disposed on the sewage manhole cover, and a power detection module. The sewage manhole cover safety monitoring subsystem communicates with the gateway through the LoRa module, and the gateway communicates with the server through the network module. By adopting the technical scheme of the invention, the system achieves the real-time monitoring and active early warning of a sewage manhole cover. Compared with a conventionalmanual detection mode, the system achieves the effect of preventing the accident in advance, and the system has a wide coverage area, is flexible in installation, is economical and reliable, is easyto maintain, and is low in cost.