Abstract: According to the time domain characteristics of UWB pulse signal, a method of moving target time delay estimation is proposed based on sliding window variance. On the basis of preprocessing echo signal, the information of variance value is extracted by sliding window, and the proposed variance is screened by double threshold after binarization, a more accurate time delay estimation is obtained after correction. Finally, the effectiveness of this method is verified by the measured data, which provides a new method for UWB radar moving target time delay estimation.