-Based on historic topographic maps and field surveys,this paper mainly deals with the forma-tion and evolution of the Jiuduansha Shoal and the North Passage and South Passage in the ChangjiangEstuary.Jiuduansha Shoal originated from the partition of the south part of the Tongsha Shoal as the re-sult of connection of a flood channel and an ebb channel.The embryo of the North Passage was a floodchannel,and that of the South Passage was the lower reaches of the former South Channel.There weretwo basic kinds of change in erosion and accumulation since the formation of Jiuduansha Shoal:continu-ous change and periodic change.The former includes the broadening of the island area,accretion on thetidal marsh and tidal flat and downstream migration of the island.The latter includes cyclic erosion andaccumulation on the two river channel banks of the island and the North and South Passages.The islandand the two bifurcated river Passages interacted on each other in erosion and accumulation changes.Atpresent,the cou -Based on historic topographic maps and field surveys, this paper mainly deals with the forma-tion and evolution of the Jiuduansha Shoal and the North Passage and South Passage in the ChangjiangEstuary. Jiuduansha Shoal originated from the partition of the south part of the Tongsha Shoal as the re-sult of connection of a flood channel and an ebb channel. The embryo of the North Passage was a flood channel, and that of the south passage was the lower reaches of the former south channel. There were two basic kinds of change in erosion and accumulation since the formation of Jiuduansha Shoal: continu-ous change and periodic change. The former includes the broadening of the island area, accretion on thetidal marsh and tidal flat and downstream migration of the island. latter includes cyclic erosion andaccumulation on the two river channel banks of the island and the North and South Passages.The island and the two bifurcated river Passages interacted on each other in erosion and accumulation change s.Atpresent, the cou