Abstract: Time delay estimation errors caused by phase wrap errors in time delay estimation seriously reduce the accuracy of time delay estimation of synthetic aperture sonar. The existing algorithm of correcting time delay estimation errors uses the quadratic function as the time delay fitting model, which does not conform to the rangevarying nature of time delays and has a large fitting error at the near range and far range, and cannot estimate the sway and heave of the vehicle. In this paper, an improved algorithm of correcting time delay estimation errors is proposed,and the range-varying function of time delay is used as the fitting model instead of the quadratic function. The numerical simulation and experimental results show that the proposed algorithm has better performance and lower computational burden in correcting the time delay estimation errors, and can also accurately estimate the sway and heave of the vehicle, compared with the existing reference algorithm. The results of motion compensation show that the improved algorithm can improve the imaging quality.