In order to study the seepage properties of fractured rock mass under the role of hydraulic fracturing, the paper adopted numerical analysis system RFPA in process of rock failure and control variate method to study the evolutionary process of crack for fractured rock mass at different angles, confining pressures, axial compression. Simulation results show that crack initiation and expansion gradually diminishe with the increase of angle of crack. The action of external conditions on crack initiation and expansion under hydraulic fracturing is not ignored. The evolution of crack is controlled by the maximum main stress.