Abstract: Due to the influence of multi-beam characteristics and water environment, the data quality of multi-beam edge beam is lower than that of central beam.By analyzing the factors affecting the sounding error of multi-beam edge beam, it was proposed that the depth data quality of edge beam can be improved by obtaining the terrain trend surface from the depth data of adjacent band central beam.On this basis, a curve fitting formula and edge beam sounding point error correction formula were derived, and it was verified by multi-beam measured data.The results showed that the depth data quality of multi-beam edge beam was obviously improved by using this method, and the depth data was closer to the real depth, which effectively weakened the sounding error of multi-beam edge beam, and can guide to improve the data quality of multi-beam edge beam.The research results can be applied to the deep development of multi-beam data processing software and post-processing of multi-beam measured data.