In the hydraulic flow field, the high frequency noise of the hydraulic servovalve is mainly derived from its own shock. Using the piezoelectric dynamic pressure sensor and amplifier, hydraulic jet pipe servovalve selfexcited vibration and noise were detected. In the test, the inlet pressure of the servovalve was controlled in 11~21 MPa. In order to make the experimental data accurate, FFT and wavelet analysis method were used to deal with the pressure oscillation signal and noise signal. According to the analysis results, the causes of the selfexcited oscillation and noise were found out. It provides method for reducing vibration and noise of hydraulic servovalve.