Abstract: A synthetic aperture sonar motion compensation method combining multiple subbands processing and robust Chinese remainder theorem is proposed to solve the problem that the phase-based time delay estimation is ambiguous due to excessive motion errors.Ambiguous time delay estimations obtained from phase difference between successive pings on multiple subbands.Subsequently,according to the relevance between ambiguous time delay estimations,the robust Chinese remainder theorem is applied to estimate the true delay.Then,the raw echo can be corrected by the estimated time delay.The field experiment results show that the proposed method can accurately compensate the influence of motion errors on imaging.After motion compensation,false targets in azimuth of package-target imaging results are effectively eliminated,and the contour of target becomes clearer.Analyze the slant-range profile of the imaging results of the cable-target,the-3 dB width of the profile is reduced from 9.05 pixels before motion compensation to 2.06 pixels after motion compensation,the degree of the imaging focus of the cabletarget is significantly enhanced.