Abstract:The theory about stress wave and its propagation is employed to analyze the effect of dynamic unloading during excavation of jointed rock mass slope under high geostress. And the change rule of permeability of joints after loosing of unloading is discussed. The results demonstrate that a sudden unloading of high in-situ stress will make a remarkable loosing effect during excavation of jointed rock mass slope under high geostress,which should be considered. The factors,such as value of unloading during excavation,modulus of elasticity of rock mass,distribution of joints,etc.,will influence the permeability by the way of affecting the openings of joints. The interface between integrated bedrock and joined rock mass is always the obvious loosing position during excavation,which gets a prominent change of permeability coefficient. For the rock mass of vertical slope which is divided vertically by a set of parallel joints with equal spacing,if modulus of elasticity of rock blocks linearly increases from outside to inside,the results of calculation present a rule that the value of permeability coefficient decreases exponentially(from outside to inside);while if modulus of elasticity is constant,there is no loosing effect of unloading during excavation.