Abstract: The Jietai Temple ancient landslide body is located in the Ma’an Mountain area in the Mentougou district of Beijing. Slope rock mass fractures and broken structures developed because of the multiple tectonic movements in history and the weathered unloading, causing a severe localized slip. In 2005, comprehensive managements, including retaining anchor, flood control and grouting were performed on the Class-Ⅰ and Class-Ⅱ platform of the ancient landslide body. However, late in 2013, a multi-component fracture developed on the floor and back wall of the main hall of the temple, as well as in the rear garden, and collapse of the slope sediments appeared in Class-Ⅲ platform at the foot of the slope, which could be the resurrection sign of this ancient landslide. To explore the ancient landslide stability and protect the temple from the secondary damage, the mechanisms and failure characteristics of landslide deformation were studied. With the hybrid Finite Element-Discrete Element Method (FDEM), a numerical model for the ancient temple landslide was set up, and the simulation results with the live GPS monitoring surface displacement curves and the failure characteristics were analyzed. The FDEM numerical model can reproduce the whole process of the ancient landslide partial cracking, expansion, cut-through, separating, slipping (or rolling), collision and stacking. Finally, according to the results, the danger zone of the temple ancient landslide body was determined, and they provide scientific basis for field slope monitoring points design.