The harnessing of the Yellow River has been paid serious attention to by every aspect of society. To start the construction of Xiaolangdi Project will make the harnessing of the Yellow River get into a new course of development. But, at the same time, it will exert a great influence on ecological environment. Based on long-term investigation and research, by using theories of sustainable development and methods of environmental evaluation, this paper analyzes the effect of Xiaolangdi Project on the environment in the areas such as the reservoir and surrounding area, the immigration area, and the fragile area of the downstream. Moreover, the tendency of the water quality changes in the reservoir area and the downstream is analyzed. It is considered that the spatio-temporal effect on environment is not well distributed. Resettlement is the key environmental issue of the project. The different application phases of the project will exert different influence on wetlands, the irrigation area of downstream, the delta and estuary. After the construction of the project, the increasing discharge of waste water in the section of Xiaolangdi to Huayuankou will be the major cause that worsens water quality. So it is suggested to formulate sustainable development countermeasures. (GIS, RS, GPS) integration technology is used to establish the dynamic monitoring system and the prediction geographic information system.