Abstract: Because of the complex natural condition and the difference of mining technology, the traditional surveying methods are difficult to describe the geometry of open-pit slope in a comprehensive way. A fully automatic open-pit slope reconstruction in three dimension based on UAV oblique camera technique is proposed. Unmanned aerial vehicle equipped with digital oblique cameras is used for image sequence acquisition in open-pit area, through feature extraction, aerial triangulation, dense matching, 3D point cloud are generated, and then through irregular triangular gridding and texture mapping, 3D model of open-pit slope are reconstructed automatically. An open-pit slope of aluminum mine in Sanmenxia Mianchi city is selected for experiment, the results show that the reconstructed 3D model can not only fully express the overall shape of open-pit slope but also maintain local features, with the characteristics of high efficiency and low cost. It is an important significance in the field of three-dimensional terrain and landslide hazard analysis in open-pit mine.