In order to reduce the noise in laser Doppler velocimetry signal, the method that Gaussian white noise was added to the simulated laser Doppler velocimetry signal was used. The high frequency coefficient zeroing method and the wavelet threshold denoising method were adopted for denoising after wavelet layering. The simulation analysis and experimental verification were carried out. The results show that, the high frequency coefficient zeroing method after wavelet layering can improve the signal-to-noise rate to get smooth graph signals and achieve an ideal denoising effect. The result is helpful to improve the accuracy of signal detection in laser Doppler velocimetry system.