Abstract: It is difficult to dredge silted sediment on the bottom of ballast tanks after VLCC(very large crude carrier)enters and anchors in harbors for replacement of ballast water in turbid waters. A new way of governing silt in the VLCC replacement of water ballast tanks is to separate the ballast tanks into the side ballast tanks and the bottom ballast tanks, and the side ballast tanks are taken as the main sediment deposition cabins instead of the bottom of the ballast tanks, so that the water inflowing the bottom ballast tanks will contain less slit. In this paper, a normality model is established for water sediment in VLCC side ballast tanks based on studies of high sediment concentration in the Zhoushan coastal waters, Zhejiang Province, China. The regular pattern of ballast water flowing into the different ballast tanks is also constructed. Tests on four schemes are made and the best structure design of the ballast tank sediment silt preferably among the four test designs is selected. The ballast tanks sediment deposition processes and laws are obtained from experiments. The analysis results of experiments show that 80％ of sediment deposition occurs in the side ballast tank, and only about 20％ of sediment enters the bottom ballast tanks. This is the first large scale model study of VLCC ballast tank sedimentation in China, and the model studies have provided a new way in controlling sedimentation in VLCC ballast tanks. The experimental results can be widely applied to deal with sediment depositions in the other large ship ballast tanks.