Three-Gorges Project has multipie influences on ecology and environment, including good and bad ones. This paper lay emphasis on the factor analysis of sudden and gradual changes and their effects. The exploitation of Yangtze Basin is of great significance in the development of our national economiy. The effects of Three-Gorges Project on ecology and environment must be thoroughly studied so as to provide the countermeasures, make the most of Yangtze Basin resources, harmonize the relationship between economic development and envira nmental improvement and give full play to the project benefit.