Research progress of networking of urban systems in China

At present, there is a consistency that the focus of urban system research has shifted from the hierarchical to network paradigm. Based on an extensive review of existing studies, this paper investigates the shift of paradigm of China's urban system research since the 1980s, and discusses the development situation, main problems, and key topics of related research on urban network. The results show that: (1) After 2010, the amount of literature about urban network has increased dramatically and become the mainstream of urban system research, while the number of studies on the hierarchy system decreased. And the existing studies mainly focus on the urban system at national level and in the Yangtze River Delta. (2) The attribute data to a certain extent compensate for the lack of data in the early urban network research. Meanwhile, although the gravity model was widely used in these studies, its suitability is gradually decreasing. (3) In contrast, the relationship data have attracted scholars' attention, which is mainly applied to the urban system research from three perspectives: enterprise organization, traffic flow and information flow. However, due to the limitations of different perspectives, a comprehensive research on multiple perspectives has gradually become imperative. (4) The identification analysis has been the dominant theme of urban network research. Visualization analysis and design for urban system is mainly supported by directed unprivileged networks and undirected weighted networks. (5) Five important aspects of urban network research in future include adjusting the research framework of national urban network, examining the physical connections between cities directly without traffic data, measuring the horizontal linkages between the outside enterprises, analyzing and visualizing the directed weighted network research, and intensifying the geospatial characteristics of urban network research. © 2019, Science Press. All right reserved.