This paper, based on the ecological theories, expounds the concept of urban ecosystem and approachs a subject of sustainable development from three angles: balance of ecosystem, symbiosis and the circulation resource.

• 为此，以生态学理论为基础，阐述了城市生态系统的概念，并从系统的平衡、共生及资源循环利用三方面来探讨城市可持续发展的途径。