Abstract: In order to solve the problem of topographic distortion caused by single beam sounding beam angle effect in complex waters, this paper proposes a single beam sounding beam angle effect correction method based on multi-scale mathematical model.This method establishes a multi-scale mathematical correction model of beam angle effect based on the morphology of the sounding-transducer beam and the three-dimensional spatial form of underwater terrain.The Horn algorithm is used to fit the slope and slope direction of key underwater points, so as to realize the correction of the sounding beam angle effect in three-dimensional space.An accuracy verification test for the depth test data of Baimakou to Longjie section in Wudongde Reservoir area was carried out, and the single beam data of the test area before and after correction were analyzed by taking the cloud data of aero LIDAR as base.The results show that the difference after the correction is mainly concentrated in the interval -0.25 m, 0.25 m,the distribution conforms to the law of random error of measurement, and the influence of beam angle effect is significantly weakened; after the correction, the mean square error of the sounding measuring is increased by 48.6%,and the accuracy of underwater survey of sloping terrain is effectively improved; it is convinced that the slope ratio of underwater terrain is the main factor affecting the beam angle effect.This method provides a new direction for the correction of beam angle effect and has some reference for improving the accuracy of single beam sounding.