Abstract: Ground-based arc-scanning synthetic aperture radar (ArcSAR) is a new ground-based SAR, which has a larger imaging field of view than linear-scan ground-based SAR, and has a wide range of applications in the field of ground disaster monitoring prospect. The paper introduces the key technology of Online SAR geological disaster monitoring and early warning system independently developed by China Nonferrous Metals Changsha Survey and Design Research Institute Co. , Ltd. The monitoring accuracy of the system is tested through simulation experiments, and the application effect of the system in open-pit mine slope monitoring,etc. Explained. The results show that the system deformation monitoring accuracy is better than 0. 1 mm, and it can continuously monitor a wide range of monitoring areas at all-time, all-weather, long-distance, and high-precision, meeting the requirements of remote online monitoring of geological disasters on high and steep slopes in mines.