Two groups of hydraulic fracturing tests were carried out on concrete specimens of different strengths with a single initial crack under different stresses. The effects of stress state and loading pattern on the crack propagation process of concrete specimens were studied. The evolution law of water pressure within crack along the crack propagation path was analyzed, and the quantitative relation for the critical fracturing pressure prediction model of concrete specimens was obtained. Results show that damages induced by hydraulic fracturing occurred to the two groups of specimens under different stresses. Besides, the differences between the critical fracturing pressure and axial pressure of the two groups of specimens were less than the splitting strength of the specimens, and the development of the sharp cutting edge under water pressure lagged behind that of the dry crack.