With the rapid development of cities in China, more city power tunnels are being constructed, and the maintenance work on these cable tunnels is becoming more difficult with higher risk. As a fast-growing city, Zhengzhou is facing a serious power cable tunnel maintenance problem. Learning from other domestic and international advanced city cable tunnel monitoring systems, State Grid Zhengzhou Power Supply Company constructed an on-line monitoring platform for its city power cable tunnel with integrated functions for cable monitoring, environmental monitoring, personnel management, etc. This on-line monitoring platform has helped to ensure the safe operation of the city cable tunnel and provide effective support for power transmission.