Abstract: Water level plummet is one of the main external factors affecting the stability of bank slope, however, the existing calculation methods need to consider the seepage effect of water level drop on bank slope through the calculation of seepage force or pore water pressure or the coupling analysis of seepage field and stress field, which are complicated and inconvenient for engineering designers to adopt. In order to analyze the influence of water level plummet on the stability of bank slope conveniently, the stress state of one point in the bank slope with and without considering seepage force was analyzed, and an equivalent relationship that the influence of seepage force on bank slope stability could be seen as the decrease of the parameter of cohesion c was obtained. Combining this equivalent relationship with the strength reduction method, a simplified calculation model of bank slope stability was established, and then a simplified stability analysis method for bank slope stability under the influence of water level plummet was proposed. The homogeneous bank slope stability analyses were carried out by the simplified analysis method in this paper, the bank slope globally critical slip field (GCSF) method, Geostudio's Slope/W module method and the traditional ultimate equilibrium methods respectively, and the results show that the safe factors calculated by the above-mentioned methods are in good agreement, with the differences of 2.6%, 3.5% and 3.5% respectively. Then the heterogeneous bank slope stability analyses were carried out by the simplified analysis method in this paper and the slope globally critical slip field (GCSF) method respectively. The results show that the safe factors calculated by the two methods are also in good agreement, with the difference of 3.1%. It is indicated that the simplified calculation method proposed in this paper for homogeneous and heterogeneous bank slope stability analysis is reliable and feasible.