Abstract: Slope instability will not only bring huge losses to industrial and agricultural production, but also pose a great threat to the safety of people's lives. At present, landslides have become one of the three major geological disasters in the world, together with earthquakes and volcanoes. Landslides are caused by a variety of factors such as reservoir water level change. The reservoir water level change induced landslides are particularly concerned. Therefore, it is of great importance to establish a reasonable slope stability analysis method for predicting and preventing landslide hazards. The actual slope instability process often occurs under the coupling effect of various loading factors. However, previous analytical methods such as the limit analysis method focus on the influence of single factor on slope stability and are difficult to reasonably consider coupling application of various factors. Accordingly, they cannot capture the path dependence of the slope stability. In this paper, we establish a model of a soil slope under the combination of top loading and water level change on the basis of the limit analysis method. We assume that the soil below the water level is subject to buoyancy and reduction of cohesion. The effectiveness of the model is verified by the centrifuge test results. The model predictions reveal that the slope stability monotonically decreases with increasing top load, and non-monotonically changes with increasing water level. Therefore, the slope stability is significantly dependent on the coupled loading process.