Abstract: In this study, the back analysis of 7·25 landslide triggered by rainfall on the north side of Fushun West Open-pit Mine was carried out, and the obtained initial water level, failure time and failure sliding surface are all consistent with the actual situation, thus verifying the correctness and effectiveness of the calculation and results. On this basis, the influence of drainage pipe failure and depth of weathering fracture zone on slope stability was studied. The calculation results show that the drainage pipe can effectively reduce the underground water level and improve the slope stability. Once the drainage pipe enters in failure state, the slope safety will be decreased, and the slope may be unstable in a shorter time under the condition of rainfall. Therefore, a regular maintenance of drainage pipe is essential for its effective work. The weathering fracture zone also has a great influence on the slope stability. Under the influence of weathering and unloading, the depth of weathering fracture zone may change dynamically, so it is necessary to enhance dynamic monitoring to ensure the safety and stability of the slope.