Abstract: Aging municipal drainage pipes are prone to defects, making inspection critical for safety. While sonar is ideal for inspecting sewage pipelines, motion errors from the sonar platform can degrade image quality. To address these challenges, this paper proposes a synthetic aperture sonar (SAS) motion compensation algorithm based on adaptive time-delay estimation. The algorithm first introduces the HVSL-MLETDE method, establishing the mathematical relationship between carrier motion errors and slant-range differences. Subsequently, the HVSL-MLETDE algorithm estimates inter-pulse time delays between adjacent pings. Finally, three types of motion errors are fitted using the least-squares method, enabling motion error compensation in the frequency domain and image reconstruction via the Range-Doppler Algorithm (RDA). Results from simulation data, sea-trial data, and pipeline inspection data collectively demonstrate that the proposed algorithm achieves precise motion error estimation. The compensated imagery closely approximates ideal performance, validating the algorithm’s effectiveness in practical applications.