High-voltage transmission tower, as an essential part of the transmission network, will inevitably be constructed in the ridge, steep slope edges and other similar areas. It may be damaged by landslides induced by short-time heavy rainfalls. This paper focuses on the problem of early warning of transmission tower under rainfall-induced landslide disaster. According to the position relationship between landslide body and tower, a quantitative classification method of landslide impact factors based on multi-source information fusion of BeiDou Navigation Satellite System (BDS) and numerical weather forecast is proposed. The risk early warning method of transmission tower through the two-factor hierarchical overlapping method is established. Finally, the validity and practicability of the proposed method are verified by a case study. Some suggestions are given according to the test results, which is helpful to take preventive measures in advance and reduce the catastrophic impact of geological disasters on the power grid. This work is supported by Science and Technology Project of State Grid Corporation of China (No. SGSDDK 00KJJS1800210) “Multiple Serious Fault Online Early Warning and Fault Disposal Decision Making Technology Large Scale Power Grid”.