There are many arguments on the causal mechanism of the tidal sand ridges off the coast of Jiangsu province since a long time. It mainly focuses on the dynamics, sand source, initiation age and developing process. Since 1980s, there have been some progresses in these problems, with the investigation on the coasts and the islands, the drilling in the region of coast and continental shelf, and the further development in tidal-system digital simulations of East China Sea. Recently, the authors have analysed sedimentary facies and depositional environment of a coast section composed of 39 cores in middle Jiangsu province coast, and have made digital simulation on the changing process of the tidal current systems in East China Sea for the last 15 000 a years. This paper attempts to discuss the dynamics, sand source, initiation age and developing process of the tidal sand ridges off the coast of Jiangsu province , in terms of the latest analytical data and the results of digital simulations basing on careful analyses of historical literatures. The results show that the main dynamics for the development of the sand ridges are the tidal current systems which convergence off Qianggang and dependence on the location and outline of the coast-line of Jiangsu province and the southern margin of Shandong peninsula. Initiation time of the tidal sand ridges is about 10,000 to 8,000, not 2,000 or 4,000 years BP. Where the sand-ridge-composed material come from is much more complex than it has been thought. In fact, it is the mixture of various sediments in and around the region of the sand ridges with the sands that were and are brought into this region during the development of the sand ridges. Because of the coastline changes since the initiation of the sand ridges, the tidal current system has been experiencing a series of adjustments. Therefore, the sand ridges must have experienced a series of destruction, constructions and adjustments. Sedimentary sequence analysis and tidal-current-system simulations give some evidence to support those changes during the past 10,000 years. The sand exposure region between 30 and 60 m depth in South Yellow Sea has been thought to be the result of erosion by ocean currents. But the ocean currents in South Yellow Sea are too weak to erode the seabed. However, the tidal currents of South Yellow Sea are strong enough to do that. Furthermore, the sand exposure regions in southern Yellow Sea match well with the distribution regions of the sand ridges in 10,000-8,500 years BP and surround the modern sand ridges. Therefore, the exposure of sand area in southern Yellow Sea is the result of erosion by tidal current, not by ocean current.