Abstract: Based on the seafloor topography survey in the Bohai Sea, four areas of sand ridges are identified, i.e. the Liaodong Shoal, the east coast of Liaodong Bay, the estuary of Liugu river and Caofeidian. Data are collected from 8 current measurement stations in the sand ridge areas. The dynamics relation between sand ridges and sand sheets are simulated using numerical modeling method. Suppose the source of sediments is available, tidal sand ridges will be developed if the M₂ tidal current elliptical semimajor is 50 cm/s to 75 cm/s, and the absolute value of ellipsoid rate less than 0.4. The direction of sand ridges follows the direction of elliptical semimajor. Tidal sand sheets will be developed if the M₂ tidal current elliptical semimajor is 40 cm/s to 50cm/s, and the absolute value of ellipsoid rate between 0.4 to 0.6. Neither tidal sand ridges nor sand sheets will be developed if the M₂ tidal current elliptical semimajor is too large or too small.