Abstract: This paper reconstructs and analyzes the changes of coastal geographical environment and the response process of human activities under the influence of the main channel swing of the Yangtze River estuary since the early Ming Dynasty, and reflects on the historical periodicity of the main channel swing of the Yangtze River estuary and related man-land relationship. It is found that the effect of the south deviation of the main channel of the Yangtze River in the early Ming Dynasty had been obviously manifested in the collapse of the coastline on the South Bank of the estuary and the attenuation of salt production. Since then, with the continuous increase of the drainage of the South Branch, the influence range of fresh water on salt production also expanded to the south. From the early Ming Dynasty to the mid-20th century, the salt fields to the north of Jinshan were shut down successively due to the dilution of seawater, and the original salt farm area was transformed into an agricultural planting area. The influence of the South deviation on the coastline, water system and water conservancy of the South Bank of the Yangtze River estuary is mainly reflected on the coastline collapse in the North and siltation in the South with Huangjia Bay as the node, rivers inside and outside the seawall connection on the siltation bank, and rivers separation by the seawall on the collapse bank.