中文摘要：

改革开放以来，中国城市化进程加速，形成了具有中国特色的城市群空间组织模式，并成为国家空间发展的重心。国务院已颁布一系列与城市群发展相关的规划，以此作为区域发展的引擎。首先，回顾了城市群研究中存在的问题，认为城市群界定必须建立在都市区基础之上，并提出了5项指标；而后利用五普数据，界定了13个大城市群，并从国家和区域层面分析了大城市群对区域经济的引领作用。其次，认为有必要从国家层面开展城市群界定的工作以推进城市化的发展，而学界则需进一步探讨城市群的功能从集聚转向扩散的规律。

英文摘要：

In the reform era, large city clusters have formed as a result of expedited urbanization in China. This paper first identifies the problems in existing city cluster researches, and then puts forward a definition of large city clusters based on metropolitan areas and five indicators. Using data collected in China＇ s fifth census in 2000, the paper defines 13 large city clusters with population of at least 10 millions, higher urbanization rate, and at least two large metropolitan areas. Among the identified city clusters, the population size of both Yangtze Delta large city cluster and Pearl Delta large city cluster exceed 50 million respectively. The paper also analyzes the leading roles of large city clusters in the national and regional development. At the national level, large city clusters are important engines of growth for the Chinese economy. In 2009, the combined GDP of the thirteen large city clusters amounted to RMB 20.3 trillion, or 59.63 % of national GDP, highlighting the further intensification of economic concentration. In particular, three large city clusters, namely Beijing-Tianjin-Tangshan, Yangtze Delta and Pearl Delta, have become centers of corporate regional headquarters, R ＆ D bases for multinational corporations, and headquarter centers for the top 500 Chinese manufacturing enterprises. At the regional level, the paper measures the economic concentration index of 13 large city clusters in terms of the large city clusters＇ share of regional GDP, and analyzes their changes. At the end, the paper points out the necessity for the government to launch a research on defining large city clusters so as to promote the process of urbanization of China while academic discussions can focus on the agglomeration and dispersion of large city cluster.