Abstract: Among the current instructions and criterions for ocean dumping sites mornitoring in China, the ones based on chemical and biological variations are relatively mature; however, little comparison and specifying have done upon the submarine topography, geomorphology, and sub-bottom profiles, As a result, the movement and evolvement of the dumped materials cannot be fully tracked, which restricts the improvement of the monitoring work in China. In this study, we took the ocean dumping site for the third class dredged-materials south off Dalian as an example, estimated the advantages and disadvantages of single beam/multibeam bathymetry, sidescan sonar seafloor imaging, and sub-bottom profiling. It turns out that, the dumping activities significantly changed the submarine topography, which could be more accurately revealed by multibean rather than single beam echo sounding. Thus the multibeam bathymetry is worth of recommending in the monitoring work. Further, the seabed geomorphology and sediment characteristics become different after dumping, helping in recognizing the dumping area, which is useful in the dumping site monitoring. Meanwhile, due to little difference between the dredged materials dumped and the local sediment, and small amount of dumping recent years in this site, it failed to distinguish the inside layers from different dumping events by sub-bottom profiling. That means, the sub-bottom profiling is helpless in monitoring such dredged material dumping sites.