In order to explore the influence of water level fluctuation and rainfall on the deformation mechanism and stability of wading landslide, taking the South Bank Landslide of Liudong in Pingtang County of Guizhou Province as the research object, the geological background and deformation characteristics of landslide disasters were analyzed through field investigation and on-site monitoring. Based on unsaturated seepage theory and limit equilibrium analysis, the stability coefficients of landslides under different combinations of water level fluctuations and rainfall at 673 ~ 685 m were calculated by using the finite element software Geo-studio, the change rule of seepage field, stress field and displacement field was obtained, and the signs of landslide deformation and damage mechanism were detected. The results show that the cumulative displacement curve of the landslide shows the characteristic of "step shape", and the deformation corresponds to the change of river level and heavy rainfall in time. The increase of rain intensity will reduce the stability of the landslide, and the stability will be restored after the rain stops for a certain period of time. The rise and fall of water level will increase and decrease the stability of the slope respectively, and the greater the rate of lift, the more pronounced the degree of change in stability. The combine effect of falling water level and rainfall is the most unfavorable conditions, precisely because the slope experienced two most unfavorable conditions from July to September 2020, resulting in the resurrection of the landslide and increased deformation. The research results can provide some reference for landslide prevention and mitigation in mountainous river banks.