Abstract: Owing to the tectonic deformations during the Indosinian,Yanshan and Xishan epochs,the tectonic environment of foreland basin in the northern edge of lower Yangtze area changes from rift,collision matching to stretch rift,and ultimately results in a structural geometrical model of "3 tiers pavilion" with stretch in the top,thrust nappe in the middle and decoupling slip in the bottom.The tectonic deformation is mainly controlled by the collision orogenesis of Yangtze and North China platforms during the Middle Triassic with the characteristics of strong-weakness zoning horizontally and deformation layering vertically.The deformation style includes 3 types: stretching deformation,thrust fold deformation and decoupling slip deformation.