The Jiangnan waterside settlements in the Taihu Lake Basin include low villages,high villages and coastal villages.In the past,most studies focused on the low and high rural areas,and few studies on the settlement forms and causes in coastal areas.Based on the perspective of"natural environment-human settlements"interactions and the influence of tides on the environment of coastal area,this paper analyzes the formation process of traditional settlements in Jiangnan coastal area from the dimensions of boiling waves and salt,reclamation of cooking fields,fortifying against Japanese invaders and setting up sand islands,and reveals the formation mechanism and morphological characteristics of four typical traditional settlements,namely saltern agglomerations,farming settlement,coastal defense settlement and zhaigou settlement.