In order to investigate the variation of shear characteristics of rock fractures after seepage erosion and its evolution mechanism, shear tests were conducted on two groups of specimens in different states. One group was fresh and the other was after a 120 h seepage-erosion experiment. The variations of shear test curve, peak shear strength, residual shear strength and initial shear stiffness were analyzed. The results show that the shear stress-strain curves and normal displacement-shear displacement curves of rough fractures after seepage erosion change little compared with the fresh rough fractures, but the shear contraction displacement decreases and the shear dilation displacement increases. The seepage erosion increases the surface roughness of the fracture, leading to an average increase of the peak shear strength by 8. 83%, but with no significant change in the residual shear strength, indicating a declined ratio of residual strength to peak strength. The initial shear stiffness increases by 10. 84% on average after seepage erosion.