Abstract：In order to probe into the damage and degradation influence of seepage pressure on brittle rock and the seepage characteristic law during the deformation of brittle rock，the brittle rock specimens collected from the Three Gorges shiplock slope and the site of Wanjazhai hydraulic power station are tested antithesesly under different stress levels. Then，the microtest，SEM，is carried out to study the failure surface of brittle rock. The testing result indicates that the seepage character of brittle rock is of district difference before and after failure. So，it is concluded that the seepage pressure makes the effect strongly on the fracture and dilatation of rock. Based on the theoretical analysis and testing study on the damage and fracture of brittle rock，the mechanism of crack initiation and micro failure of rock under seepage pressure is gotten clearly. And，reliable testing basis is offered to analysis on the weathered rock instability of high slope under the condition of water pressure suddenly rising or falling during the oozing of rainstorm.
