Abstract: Based on the element-free method,the crack propagation in rock mass was traced under coupled mechanical-hydrological environment,in which the seepage field and stress field were coupled by the iterative computation and the interaction between two fields was considered mainly by seepage pressure and permeability coefficient.In addition,hauling force acted by water flow to crack wall was also taken into account.First,the theory of the maximum surrounding primary stress was applied to judge whether crack started splitting and continued or not and to get the propagation orientation of crack.Then the coupled analysis of seepage field and stress field was made for new structure until the crack stopped splitting.Calculation examples show that the present method can reflect the action of water flow to crack propagation and can approximately simulate the process of crack propagation under coupled mechanical-hydrological environment.