Abstract: There always exists Doppler speckle in the Doppler signal time-frequency representation obtained from short-time Fourier transform (STFT) based commercial analyzers.In the present study,a new method based on Wiener-khintchine theorem and window function was used to reduce Doppler speckle.Time-frequency representation computed using this new method was compared with those computed using the STFT,and the final results showed that this new method has the better performance on reducing Doppler speckle and can generate a more accurate time-frequency representation.