Abstract: Motion error is the main factor that degrades the high resolution of synthetic aperture sonar (SAS). Based on the analysis of the characteristics of the range-variant motion error and the study of the segmenting strategy, a motion compensation method to divide echo data into non-uniform segments is proposed for wide-swath synthetic aperture sonar. By means of dividing uniformly along the ground range, non-uniform segments, which are consistent with the first-rapid-then-slow range variance of motion error and then could get compensated more accurately, can be obtained along the slant range through the effect of the range compression. Simulation results show that after non-uniform segment motion compensation, the peak side lobe ratio of the target declines, the contrast between the target and the background gets enhanced and the difference between the nearby targets and distant targets gets reduced. The proposed non-uniform segment method takes different measures to deal with echo data with different range variance, which has an obviously improved performance especially for nearby targets in the application of the wide-swath synthetic aperture sonar.