From the aspects of four ecological themes, i.e., ecological element, ecological process, ecological function and ecological destruction, an indicator framework including 16 indicators was developed to make an integrated assessment on the ecological quality of Beijing urban area. The weights of the indicators were determined by the methods of entropy weight, optimal state weight, and worst state weight, and the ecological element index (EEI), ecological process index (EPI), ecological function index (EFI), ecological destruction index (EDI), and composite ecological index (CEI) were computed by a weighted sum method and served as effective tools for analyzing the evolvement of the ecological quality of Beijing urban area from 1996 to 2005. The results showed that during the period of 1996-2005, the EEI of Beijing urban area did not display visible improvement and maintained a low level, far from the ideal state. The EPI and EFI increased dramatically, and approached to the ideal state in 2005. The EDI fluctuated within a low level, far from ideal state, and did not show an evolutionary trend. The CEI improved year after year, but was still low and did not reach the ideal state. The EPI, EFI, and CEI increased rapidly with economic development when the GDP per capita was less than US $ 3,000, but the decrease was decelerated after the GDP exceeded US $ 3,000. The EEI and EDI were less affected by economic development, but mainly restrained by the natural conditions and global and regional eco-environmental evolvement.