Abstract: In the power system, underground cables have increasingly replaced overhead lines, which not only enhances the safety of power system operation but also beautifies the traffic roads. With the large-scale operation of cables, the safety of underground cable ducts has become a major concern. To enable maintenance personnel to promptly identify potential safety hazards in cable wells, this paper designs a cable well condition monitoring system based on RS-485 communication. This system can monitor six major safety hazards in cable wells, including the force on the well cover, well cover displacement, water immersion height, methane concentration, hydrogen sulfide concentration, and carbon monoxide concentration. When a hazard is detected, it triggers an alarm function to alert maintenance personnel for handling, thereby improving the safety of cable operation and the safety of people′s lives and property.