Abstract: The permeability-strain curve and permeability-stress curve can be obtained based on permeability test under complete strain-stress path.Analyzing the connections of permeability rate,strain and stress before rock ruptures,the concept of critical antipermeability strength of rock is prolided.As a characteristic parameter during rock distorts,this paper proposes the engineering significance of critical anti-permeability strength of rock,and introduces an example of application of the characteristic parameter to evaluating water-insulating capability of the coal seam floor when mining with pressure.