Self-made cement mortar was used as the rock-like materials to test the law of rock destruction under the coupling effect of water pressure and uniaxial axial compression. Under the premise of steady hydrostatic loading speed and axial pressure, cube specimens of different material strengths and sizes with prefabricated cracks in the center were made to perform hydraulic fracture tests by a self-developed hydraulic pressure and axial compression device. The results show that the axial compression loading direction has some influence on the crack initiation angles, and the rising of the internal water pressure is positively correlated with the strength of the specimen at a steady hydrostatic loading rate. The axial compression loading direction, whether parallel or vertical to the prefabricated cracks, can accelerate the rising of internal water pressure. The critical internal water pressure of hydraulic fracture is positively correlated with the strength of the specimen. The axial compression loading direction has a greater effect on the hydraulic fracture of a specimen with a single crack. When the axial compression direction is perpendicular to the direction of the prefabricated fracture, the crack initiation is inhibited. On the contrary, when the axial compression direction is parallel to the prefabricated fracture direction, the crack cracking is promoted.