Study on Yangtze River Delta city network based on complicated network

With the development of globalization and regionalization, the correlation among cities is growing and evolves to complicated network. This study aimed to seek the basic methodology for regional city network and reveal the unseen characteristics in the network, taken the 16 cities in Yangtze River Delta as empirical study. By calculating the economic relation matrix with city line weighted, computing betweenness closeness, eigenvector centrality and clustering coefficient, this paper demonstrates that: the regional network is closely connected but unbalanced distributed, Shanghai is center followed by Hanghzou Suzhou Nanjing with the thickest economic connection, while Zhenjiang, Shaoxing etc has their own feature, Yangtze River Delta cities have formed a good agglomeration. There is a strong correlation between cities economic level and network level. Finally, the paper diagnoses that Shanghai should improve its diffusion and radiation effects, other key cities should focus on sustainable development; while the fundamental cities have to make up their economic weakness. This research is important, it extends the world city network to regional level, further explores the methodology to establish regional urban economic network statistically, theoretically and empirically.