The self-excited oscillation pulsed water jet (SEOP Jet ) has been used extensively in oil and gas well drilling, mineral mining, cutting and industrial cleaning. In order to improve the valid stand-off distance of water jet pressure and its range of action, the model of oscillation frequency of jet was given on the basis of hydroacoustics and fluid dynamics for better understanding the principle of increasing jet pressure amplitude. The SD150test system was used to analyze the effects of dynamic parameters on the frequency, the effects of pump pressure and the cavity length on the frequency were studied in detail. The test results showed that the peak value of the SEOP Jet is larger by about 20% than that of continuous jet. The oscillation frequency increased while increasing pump pressure and decreased while increasing cavity length. There was an optimum cavity length corresponding to the pressure peak value of the SEOP Jet. Experimental result is in good agreement with that of theoretical analysis.