Aiming at the impact of ground water under water level fluctuation on landslide stability, take a landslide on Reservoir Bank for example, use a simplified analysis method on phreatic surface, phreatic surface is determined considering the permeability coefficient, the rate of water level fluctuation and the other factors in Seepage Field. On this basis, the stability of this landslide is calculated with limit equilibrium method, it is founded that the change law of the stability is down-up when the water level downs. Then stability is calculated at three different rates of water level descending, different rate of decline in water levels also affect the stability of landslide. It proved that the stability decreased when the rate of the water level descending grows. And when the water level descend at these rates the stabilities all decreased gradually to a minimal value first, then it all increased after the water level decreased to a depth.
