Objective To investigate the microstructure characteristics in human kidney with the WD cepstrum of ultrasonic backscattering. Methods By using this method, an analysis of the backscattering signals of normal and pathological human kidney in vitro was made and the mean spacing of the scatterers of biological soft tissues was estimated, then compared the means of this new approach with the means of the AR cepstrum. Results The results show that the mean spacings of the scatterers of the two different kidney tissues are noticeably different, which reveals the fact that the WD cepstrum works more effective than the AR cepstrum in showing the features of the microstructure of soft tissues. Conclusion The WD cepstrum is an effective mean to analyze the ultrasonic scattering signals and determine the features of the mean spacing of the scatterers of soft tissues. This method provides more available clinical diagnosis and improves the results of mean spacing of the scatterers of soft tissues.