Tidal current ridges, widely distributed geomorphological phenomena over the continental shelf of the world, are studied. They are formed by tidal current and the trend of their sand bodies runs parallel to the direction of tidal current. There are two types of the plane shapes: the parallel and the fingered. Conditions of forming tidal current ridges are the velocities of tidal current ranging from 1 to 3.5 knots and the supply of abundant sediments. Tidal current ridges often develop in following morphological locations: the bays, estuaries, the mouths of channels, as well as the offshore area with strong tidal current. Tidal current ridges occur generally at a water depth of less than 35 metres.The sediments of tidal current ridges are mainly composed of sand. The grain size of the sedi-ments is uniform and well sorted. The characteristics of grain size of the sand imply that their formation mechanism is similar to that of river sand, that is, both of them are the result of flow movements in A trough Tidal current ridges, widely distributed geomorphological phenomena over the continental shelf of the world, are studied. They are formed by tidal current and the trend of their sand bodies runs parallel to the direction of tidal current. There are two types of the plane shapes: the parallel and the fingered. Conditions of forming tidal current ridges are the velocities of tidal current ranging from 1 to 3.5 knots and the supply of abundant sediments. Tidal current ridges often develop in the morph morph locations: the bays, estuaries, the mouths of channels , as well as the offshore area with strong tidal current. Tidal current ridges occur generally at a water depth of less than 35 meters. The sediments of tidal current ridges are mainly composed of sand. The grain size of the sedi-ments is uniform and well sorted. The characteristics of grain size of the sand imply that their formation mechanism is similar to that of river sand, that is, both of them are the result of flow mov ements in A trough