3D modeling and visualization of the slope body is an essential prerequisite for objective evaluation of open-pit slop stability. Taking an open-pit slope where a small scale landslide happened as the study object, open-pit slope sequence images were first obtained from unmanned aerial vehicle(UAV) with a consumer-grade camera. And then, dense 3D point clouds were generated based on computer vision technology. Finally, high-resolution 3D digital models of open-pit slope were made. The experiment shows that the presented method can quickly construct an open-pit slope fine terrain, effectively reduce the operation cost and labor intensity. Moreover, due to this technology breaks the limitation of traditional method of single point measurement, reconstructed model can accurately expressed the global and local characteristics of open-pit slope, which can provide powerful support for the correct analysis and evaluation of slope stability, especially suitable for dynamic deformation monitoring of the potential risk open-pit slope.