Tianshui is located in the faulted zone at the northern edge of the West Qinling Mountain. The active faults in the area are well developed. According to historical record, the earthquakes used to happen frequently. A large number of loess landslides have been induced in this area. Based on field investigation of the north mountains landslide group in Tianshui, the authors studied the deformation and failure characteristics of the earthquake landslide. Taking Hongqishan landslide as a typical case, combined with laboratory test results, the authors analyzed deformation mechanism of Hongqishan landslide, and then applied FLAC^3D to simulate the stability of Hongqishan landslide. The results show that the north mountain landslide group in Tianshui is induced by earthquake action; Hongqishan landslide contains two main slip belts, and it has experienced more than 3 deformation activities in history. Its evolution process is complicated and belongs to earthquake-rainfall coupled landslide; Nowadays, the Hongqishan landslide is relatively stable under the natural condition. If a strong earthquake occurs, it will cause a breakthrough of the plastic zone inside the slope, and the soil on the top of the slope will slip. The research results can provide a basis for the deformation mechanism and disaster prevention of the earthquake landslide in the potential strong earthquake area.