The Ningwu basin is a mesozoic pull-apart basin that developed along the Fangshan-Nan-ling sinistral shear fault and the Binjiang sinistral shear fault in the Tancheng-Lujiang fault zone in eastern China, It formed in Late Jurassic and withered in Late Cretaceous.According to the characteristics of sedimentary formation, volcanicity, magma activity and mineralization of the Ningwu district, a model for formation and evolution of the Ningwu Pullapart basin has been put forward, by which the whole evolution process of the basin is divided into four stages: (1) germinal stage-basin nucleation, (2) young stage-"s-shaped" basin, (3) mature stage-roomboidal basin and, (4) withered stage-extreme development. The Ningwu pull-apart basin was characterized by intensive volcanic activity. Especially because of su-bvolcanic intrusion of intermediate-basic rocks with more alkili and less silica, the important porphyrite iron deposits of the Ningwu district were formed during late "s-shaped" basin stage.The tectonic stress field of the Ningwu pull-apart basin has been changed continuously with development of the basin. The general terned of the change is that the extension area of the basin expanded gradually and at the end, the extension was throughout the basin in the extreme development stage. The result of numerical simulation shows that the tension stress trending NNE-NE is several times large than the compression stress trending NWW-NW. It means that the Ningwu pull-apart basin has formed and developed under the action of this strong tension stress.