Abstract: This paper is based on the analysis of landslide and a large number of predecessor research results. It summarizes the works of conventional numerical simulation in the analysis of stability, landslide mechanism analysis and reproducing sliding process. It presents the basic conditions of numerical simulation applicable to geo-hazard emergent rescuing. At the same time, it puts forward the state differences between conventional and emergency numerical analyses. It clearly figures out the characteristics of emergency numerical simulation, and the key problems about the application of numerical simulation to geo-hazard emergent rescuing. It gives an application example of the Wangshan-Zhuakousi landslide on the Mount Emei, Sichuan province. It uses the numerical method of discontinuous deformation analysis(DDA) that has outstanding advantages in the analysis of large deformation in real time. The numerical simulation in the process and reason of the landslide have been taken into a further study. The results show, the sliding process is successfully reproduced and the maximum horizontal displacement of the sliding body reached by DDA mode is 87meters. The peak speed is 7m·s^-1. The results show that sliding distance is about 38meters and the leading edge thickness is 53meters. The whole duration of the landslide obtained by DDA method is about 70 seconds. The numerical results are consistent with the results of emergent investigation. It's concluded that numerical simulation in geo-hazard emergency is good for the comprehension of the process of landslide, finding the key point and auxiliary emergency decision.