Abstract: This paper systematically analyzed the geological and hydrological conditions of 64mining area in Baishan mine and tested the physical and mechanical property of weathering bedrock,aquiclude and aquifer.Then,The influence of rock argillization on roof fracture and its permeability were studied and the minimum protective rock pillar was obtained accordingly.Field practice shows that:the softening,argillization and weathering of rock could reduce the roof fracture height,which be beneficial to coal miming under such area.