Abstract: High-level collapse disasters are typical and frequent geological disasters in mines, which often result in huge economic losses and even casualties. Taking the Shijia Mine in Hejin City as the research object, based on the existing geological data and field surveys, the characteristics of collapse development and instability mode types were analyzed, and the instability process of dangerous rock masses was simulated by Rocfall. The results show that the study area is disturbed by mining to form a high and steep bare rock slope, with steep dipping fissures developed, and the dangerous rock mass will reach the limit state under the action of differential weathering, which will eventually lead to collapse disasters. A large number of dangerous rock masses are still developed in the middle and upper part of the slope, with varying degrees of weathering, which can collapse and collapse within an uncertain time. The causes of collapse in the area are all unloading-cracking types, which are divided into slipping type, overturning type, bulging type, and falling type according to the characteristics of the dangerous rock mass. Through numerical simulation, the theoretical path diagram, bounce height, total kinetic energy, translation speed and the distribution characteristics of the stagnation position of the dangerous rock instability movement were obtained, and it was found that the dangerous rock falling has an impact on the road, platform, and factory building at the foot of the slope. There are a large number of limestone mines in Hejin City, and long-term disorderly mining has caused serious damage to the geological environment in the area. The Shijia Mine is large in scale, severely damaged, and has a certain representativeness. By studying the characteristics of the slope collapse and instability, influencing factors and kinematic characteristics of the Shijia Mine, it provides a certain theoretical basis for the identification and control of the mine geological disasters in Hejin City, which is of practical significance.