Wuliangsuhai is the large-scaled multi-function lake-wetland with high ecological and social value in the semi-desert area of China, the biggest freshwater lake in the Yellow River basin, and also the unique carrying and drainage way to the Hetao irrigation area. The major recharge sources of Wuliangsuhai wetland are irrigation return with high-density nitrogen and phosphorus, industrial wastewater and sewage. On the basis of Landsat TM or ETM data of 19 years from 1986 to 2004, integrating with historical materials, the impacts of human activities on the wetland water environment were analyzed. These impacts mainly include the increase of artificial reeds area and dense water weed area, the deterioration of water environment, the rising of lake eutrophication, and the reduction of aquatic resources. Though the applications of the project diverting water from Yellow River to Wuliangsuhai wetland slow down the process of the deterioration of the wetland environment, the Wuliangsuhai wetland still confronts with serious threat.