The Yangtze River Delta Urban agglomeration，Urban Agglomeration in the middle reaches of the Yangtze River and Chengdu-Chongqing Urban Agglomeration are the important engines to support and lead the high-quality and integrated development of the Yangtze River economic belt，and are also important functional areas in the strategic pattern of regional development in China. Based on the statistical yearbook and statistical bulletin data，this paper mainly analyzes the economic development characteristics of the three urban agglomerations. The main conclusions are as follows：In recent years，the regional economy of the three urban agglomerations has continued to decline，but it is located in the medium and high-speed growth range. The total GDP has increased significantly，and its proportion in the Yangtze River economic belt and China’s economy has steadily increased. The level of development has been steadily improved，but there is a big regional gap. The economic growth rate of the nine core cities slowed down，the total GDP increased，and the development level improved. Compared within the urban agglomeration，the growth rate of core cities is slow，the scale advantage is obvious，and most of the development indicators are in the lead. The economic development of the three urban agglomerations will face severe challenges in 2020. Due to the different development status，the next key development tasks of the three urban agglomerations are different. There are obvious development gaps among the core cities. In order to promote the high-quality development of urban agglomerations，it is necessary to enhance the development level and function of core cities.