Abstract: During the operation of the Three Gorges Project, the reservoir water level changes according to the actual condition of water storage and hydrologic condition. Because of the correlation between the underground water level of landslides and the reservoir water level, water level cyclical fluctuation may have effects on the landslides in many ways. The effects cause the changes of the stability of landslide in the reservoir area. Permeability is the internal property of landslide. The permeability coefficient can be used to characterize the hydraulic conductivity of the soil. It is also the main factor influencing the characteristics of seepage field of the landslides on the reservoir bank. The stability of the landslides responds differently to the changes of the reservoir water level, due to different permeability of the landslides. According to the statistics of the reservoir water level of the Wanzhou, we take the Xiaping landslide in Wanzhou district of the Three Gorges Reservoir area as a model. We study the variation law of the stability of landslides with different permeability coefficients by analyzing the characteristics of seepage field under 4 different orders of magnitude of permeability coefficient. The results show that the variation of the stability of this type of landslides shows highly positive correlation with the variation of the reservoir water level. The worst stability of the landslide appears when the water level is dropped to the lowest level. And the faster water level drops, the worse the stability of landslide becomes. The regularities of the coefficients of landslide stability changed with the time are almost the same under different permeable conditions. The variation ratio of the coefficient fluctuates within a certain range between-2% to 2%.The maximum and minimum of the landslide stability go after the permeability. As the permeability of the landslide decreases, the response of the groundwater to the reservoir water level fluctuation becomes more and more weak. The minimum of the landslide stability shows an approximately exponential relationship with the logarithm of permeability coefficient. The maximum of the landslide stability shows an approximately logarithmic relationship with the logarithm of permeability coefficient.