Abstract: Abstract: In the deep mining process of the mine, the slope forms a high-risk surface with broken structure and steep slope, which is very easy to cause geological disasters of collapse and slide. It is of great significance to study fast and effective monitoring technology for effective prevention and control of slope engineering disasters and mining volume monitoring. In this study, the fixed-wing UAV aerial survey method was used to acquire three-dimensional point cloud data of large open pit mines, and DEM data was generated by point cloud denoising and vegetation removal. According to DEM data, the slope data of mine slope is extracted and the risk analysis of slope is carried out. By using the multi-period DEM difference to obtain the open-pit mine changes and achieve effective monitoring of mining activities. The results show that the aerial survey technology of UAV can quickly and effectively obtain the 3D real scene model of large open pit, and can provide visual data support for government and enterprises. The slope data extracted by terrain analysis from the large-scale open pit mining DEM data can effectively find the slope collapse phenomenon.Multi-period DEM difference data from large-scale open pit mining can achieve accurate monitoring of the amount of mining changes.