Abstract: The stability of open-pit mine slope is a critical factor to the safe and sustainable mining and it changed continuously due to the mining activities, so it is of great significance for the mining production safety to use the advanced practical monitoring technologies so that the large scale open-pit mine slope can be real-time monitored and early warned continuously.The monitoring and prewarning system is established in an open-pit mine in north China based on the synthetic aperture radar and the surface displacement of slope is investigated in this paper.The monitoring and early warning data show that compared to some traditional point monitoring technologies like GNSS, the synthetic aperture radar system had obvious technical advantages.It could provide high accuracy monitoring to the whole open-pit mine slope simultaneously and it could also make uninterrupted, continuous tracking and early warning in real-time on the slope deformation process.The synthetic aperture radar system could identify accurately the critical deformation area, which provided accurate data basis and useful technical reference for cold area open-pit mining slope safety management.