As an important spatial form of regional spatial organizations, urban agglomeration has become an important aspect of rapid urbanization because it gradually leads to a highly concentrated region with large eco-environmental problems. Night time light image was adopted to analyze spatial expansion in the Beijing-Tianjin-Hebei, Yangtze River Delta, and Zhujiang River Delta urban agglomerations. We also analyzed the regional characteristics and areas that are sensitive to environmental problems, including air quality, comprehensive use of industrial solid wastes, and vegetation coverage. Spatial expansion of the three urban agglomerations is increasing and interlocking regions of urban land have gradually formed. The interlocking regions were largest in the Yangtze River Delta and smallest in Beijing-Tianjin-Hebei area. The regional characteristics for the three urban agglomerations are presented in terms of air quality, comprehensive use of industrial solid wastes, and vegetation coverage. The air quality in the Zhujiang River Delta cities was highest and lowest in the cities that make up Beijing-Tianjin-Hebei. The comprehensive use of industrial solid waste in the Yangtze River Delta cities was highest, but was lowest in in Beijing-Tianjin-Hebei. Vegetation degradation in the Yangtze River Delta was most serious, but was least serious in Beijing-Tianjin-Hebei. The air quality and comprehensive use of industrial solid waste regional characteristics were correlated with spatial expansion in the three urban agglomerations. There was a positive correlation between urbanization level and the comprehensive use of industrial solid waste as well as between urbanization level and vegetation coverage. Areas that are sensitive to poor air quality, the comprehensive use of industrial solid waste, and vegetation coverage were identified, and the sensitive areas were correlated with spatial expansion characteristics in the three urban agglomerations. Spatial expansion was faster in Ningbo and Beijing (cities in the Yangtze River Delta and Beijing-Tianjin-Hebei, respectively), which were sensitive to poor air quality, industrial solid waste, and vegetation coverage. Zhongshan in the Zhujiang River Delta was sensitive to the comprehensive use of industrial solid waste and vegetation coverage. The analysis of regional characteristics and environmentally sensitive areas is important if environmental protection and sustainable development is to improve.