Abstract: Abstract: In the multibeam bathymetric survey, the internal waves of the ocean have different degrees of influence on the accuracy of multibeam bathymetric data. Abnormal phenomena, such as undulation and distortion of the measured terrain, are always observed. Summarizing the research status both at home and abroad, this paper presented an outline on research progress in ocean internal waves, especially the research on the causes and effects of oceanic internal waves, and the basic characteristics of ocean internal waves. Based on the analysis of real cases, the causes of the internal waves in the testing sea are carefully discussed.