With pulsed water-gas jet nozzle the pulsed water-gas jet was formed by entraining and mixing the air in the self-oscillating pulsed jet. At the pump pressure of 7.5 MPa made two groups of erosion experiments on the compressive strength of 6.9 MPa concretes. For the first group analyzed and compared the erosion effects of the pulse water-gas jet and the pulse jet under different cavity lengths, and for the second group analyzed the erosion effects of the pulse water-gas jet under different pore diameters. The experimental results show that at certain pump pressure and under the suitable cavity length, the pulse water-air jet has better rock breaking effect than the pulse jet, and there is the best air injection means which reaches the peak value of the breaking volume for the pulse water-air jet.