Abstract: To obtain characteristic pressure signals in the cavity of a self-resonating water jet nozzle, a detection system was built by using micro high-responsive pressure sensors. The characteristics of self-resonating water jet were studied and the nozzle's structure was designed. The sensors' layout was determined based on computational fluid dynamics (CFD) simulation results, and the respon-sive frequency of the sensors was determined according to theoretical calculations of the nozzle's self-excited oscillation frequency. The Hilbert-Huang transform was used due to the nonstationarity of pressure signals in the cavity. It is found that the pressure oscillation signals are focused on the frequency band of 40-60 Hz, 110-150 Hz and 200-310 Hz, and each frequency has different fluctuation am-plitudes. Pressure signals near the water outlet reach larger amplitudes with narrow bandwidth.