During the last few years, the Yangtze Delta has shown some new trends and characteristics on urban development along with its maintenance of the greatest economic core region in China. The city group, with Shanghai as center, having strong economy, highly developed society and advantageous invest environment, is taking shape. The rapid progress of regional urbanization leads this area into a megalopolis. From the perspective of general trends of megalopolis all over the world, this paper briefly focuses on the formation, development process and the present status of the Yangtze Delta Megalopolis. The megalopolis is composed of central cities, cities axles and sub city groups. An urban system with 5 hierarchies has formed. Industrial structure has been in upgrade. External economy has developed rapidly. Modern infrastructure network has taken shape. It concludes the dynamics of the Yangtze Delta Megalopolis on 4 points: (1) the transfer of government power to lower level, (2) the modification of administration area, (3) the multification of investers, (4) the establishment of markets as to the development of personal enterprises.