Abstract: Allen theoretically derived model of Twin City and developed theory of regional spatial structure, basing on a large quantity of experimental analysis on America. Suzhou, which rises rapidly impulsed by the oversea investments after 1990, has constructed the paragenetic relation on function with Shanghai, i.e. Twin City model. The formation of the model is derived from two reasons. One is the administration reason that the management costs and industrial policies of Suzhou and Shanghai have obvious differences since 1980, because they belong to different provinces. The other is economic reason that Suzhou is located in the inner circle of Shanghai municipal circles that radius is 100 km and about 50 km away from Hongqiao airport. The formation of Suzhou-Shanghai Twin Cities by the rising of Suzhou generates versatile regional effects. Suzhou and Wuxi, with the same development level and industrial property originally, now have different tendency of development. This gives them the basis on the reasonable division of function. Suzhou, which is located on the boundary of two provinces, and Nanjing, which is the capital of Jiangsu Province construct the generalized dual-nuclei structure model. We build the multiple spatial composite model of reasonable division of function of cities along Shanghai-Nanjing railway, by the comprehensive action of above-said factors. We generalize the formative condition of Suzhou-Shanghai Twin City model and analyze the formative condition and possibility of Twin Cities at others area in China as Hong Kong and Beijing.The rising of Suzhou drives scholars to discuss the ideal spatial structure form of cities along the Shanghai-Nanjing railway in Jiangsu province, observed by theoretical level. In definition the dual-nuclei structure is composed of the regional center city and port city. The connotation and application range are expended widely by inducing the definition of margin effect. Although border cities are not near large river, they have the dominance of margin effect, because they have difference on economic, management mechanism and ethnical culture. The combination of regional center city and border city also is one of the representations of the dual-nuclei structure model. The border city is referred to not only the city between two countries that is named borderer city, but also the city between two provinces that is named boundary city. The border city and boundary city are called margin city together. The combination of regional center city and port city is the primary form of dual-nuclei structure model; the combination of regional center city and margin city is the secondary form of dual-nuclei structure model. The evolution of spatial structure in Yangtze delta is effected deeply by the rising of Suzhou and the relocation of cities near Suzhou. In fact, the cities near Suzhou all take some corresponding strategies in recent years, as 173 planning of Shanghai and exploitation planning of Hangzhou bay. How to accept challenge is the main task of Suzhou to be relocated in Yangtze delta.