Abstract:In nature,the instability of slope,which can lead to landslide,is related to the participation of groundwater,which results from water permeation. Through the theoretical and practical study,the influences of groundwater on slope can be generalized into five aspects,(1) softening of rock or soil mass and discontinuities,(2) hydrostatic pressure,(3) hydrodynamic pressure,(4) increasing of moisture content and unit weight of rock or soil mass,and (5) physical and chemical action between rock and groundwater. In order to better understand the above influences,a model test on slope stability was performed. In the test,a homogeneous slope model with soft interlayer was made. Applying similarity factors,the effect of variation of surface water permeation on homogeneous slope stability was drawn through the model test. During the test,the four models were taken into account, (1) water filled in back fissures,(2) front flood fluctuation,(3) rain-fall on slope surface,and (4) combination of above three models. At last,the relationship between water permeation and slope deformation,and the dangerous amount of water permeation in slope are obtained.