Abstract: The stability of rock slopes is one of the most critical issues for the safe production in an open-pit mine. Providing early warning signals and issuing accurate evacuation orders for the rock landslides is of practical engineering significance. By collecting and analyzing 32 rock landslide cases in open-pit mines, it is proposed that the rockfall or slope movement acts as a precursor of early warning of the rock landslides. Following the safety monitoring standards for open-pit mines, the abundance of monitoring videos can provide valuable data for the early warning of rock landslides. In this study, the motion target tracking algorithm is utilized to identify rockfalls or slope movement areas from the monitoring videos. By setting appropriate thresholds, early warnings with leading time ranging from tens of seconds to hours can be provided for the areas where landslides have initiated but not yet spread. An undisclosed open-pit quarry and the Yanshan open-pit mine are employed to demonstrate the proposed method. The results indicate that the rock landslides progress through four phases including occasional rockfall, small-scale rockfall, continuous rockfall and overall landslide. For the rock landslides with heights of 6 m and 30 m, the early warning leading time is 35 s and 113 s, respectively. The proposed method for early warning of landslide of rock slopes based on rockfall video monitoring holds extensive application prospects in open-pit mines. However, extensive field tests and further research are required.