Abstract: Proceeding from the concept of integrity and systematicity of the basin,relationships of the water environment quality of the Taihu Lake Basin with the social economy,resources exploitation and other human activities in that region were investigated and analyzed and so was the need for early warning of water environmental risks of the basin.On such a basis,overall objectives and structural design of the water environmental risk early warning system was put forth,and such an early warning system was built up integrating three sub-systems,early warning program customization,early warning model library and three-dimensional display of prediction results,thus laying down a solid foundation for water environment risk assessment and setting up of an early warning platform for the Taihu Lake Basin.