Abstract: This article introduces a monitoring system for transmission line steel pipe rod settlement monitoring system. The system relies on core technologies in the field of secure IoT, such as single-tower target disaster prediction and overall risk prediction of towers in the region, to create a secure IoT support platform for the subsidence of steel pipe towers in power transmission lines, providing overall solutions and system services throughout the life cycle. The system is based on the BeiDou Satellite Navigation System (BDS) and tilt monitoring and warning technology, with the output of the BDS’s raw data, including carrier phase observation data, ephemeris data, etc., as the core. The data is transmitted to the control center via 4G wireless network. The control center calculates the three-dimensional coordinates of each monitoring point in real-time through monitoring software, and then forms real-time differential data under different monitoring systems or environments according to the comparative analysis of real-time displacement data. Finally, the deformation of the subsidence area of the power tower is corrected according to the differential data and detailed data. This system can effectively prevent various accidents caused by tower inclination and improve the safety operation level of the power grid.