Abstract: The enhancement of ability and intensity of social and economic activities has made particular ecosystem damages extend to regional eco-environmental problems. Facing a series of eco-environmental problems, social development under rapid urbanization is no longer economic growth, but the coordinated development of population, economy and eco-environment. Especially when urban agglomeration becomes the new units for global competition and international division of labor, evaluating and identifying its developmental pattern between eco-environment and urbanization has practical significance for achieving sustainable development. The Yangtze River Delta Urban Agglomeration (YRDUA) has paid a great price for its burgeoning urbanization and industrialization, which gradually became one of the new ecologically vulnerable zones in China. With reference to the Technical Criterion for Eco-environmental Status Evaluation (HJ/T192-2006) published by the Ministry of Environmental Protection of China in 2006, we selected Biologic Abundance Index (BAI), Vegetation Cover Index (VCI), Water-net Density Index (WDI), Land Deterioration Index (LDI) and Pollution Load Index (PLI) as the Ecological Index (EI) to reflect the comprehensive eco-environmental quality (EEQ).The basic characteristics and spatiotemporal pattern of EEQ in the YRDUA during the Eleventh Five-Year Plan Period (2005-2010) was analyzed. Furthermore, we took the 25 cities in the YRDUA as analytic units and discussed its status and spatial differentiation of developmental patterns between eco-environment and urbanization under the perspective of "population-economy". The results showed that: (1) the averaged EI in the YRDUA was 56.0 in 2005 and 57.3 in 2010, which was higher than the national average and were both belonged to the "moderately high" level. Concerning to the spatial distribution, the EEQ demonstrated pronounced variability, with the Shanghai-Suzhou-Wuxi-Changzhou-Nanjing belt as a demarcation belt. The EEQ of Lishui in Zhejiang Province ranked the best and Shanghai the last in terms of administrative unit. (2) During the Eleventh Five-Year Plan Period, the EEQ in the YRDUA kept steady growth. The proportion of significantly better areas was up to 10%, mainly distributing in Zhejiang Province and Shanghai-Nanjing belt. It was policy-induced emission reduction that gave rise to the overall eco-environmental improvement, followed by an increase in the volume of water resources and land degradation. On the contrary, the biological abundance reduction as well as reduced vegetation cover caused by land use change resulted in some regions' deterioration of the EEQ. (3) Most cities remained sustainable in terms of the developmental pattern between eco-environment and urbanization, but a direct consequence of industrial structure and economic base led to disparity in the developmental trajectories. Some cities including Shanghai presented economy-advancing coordination while other cities such as Suzhou and Hangzhou were in ecology-advancing coordination. On the other hand, 5 cities in northern Jiangsu showed an ecological vulnerability pattern, which indicated economy and urbanization had a strong coercing effect on the eco-environment.

Key words: eco-environment, assessment, urbanization, Yangtze River Delta Urban Agglomeration (YRDUA)