With development of economy and continuous improvement of public environmental consciousness, the requirements of water quality and water environment have been improved constantly. Water environmental issues especially, water quality problem has been the bottleneck problem and restricts social economic sustainable development in China. However, there were not any proper methods or standards that could be used to determine protection and control boundary for water environment management clearly, thus, it′s difficult to protect the water environment effectively. According to “Urban Blue Line Management Method”, firstly the protection line and the control line for water environmental management under watershed scale were proposed in this paper. They were boundaries around which rivers, lakes and wetlands in watershed needed to be restrictedly protected and their meaning was expanded to emphasize watershed as a plan unit in this paper. Similar to riparian buffer, the protection line with a constructed vegetation belt played a key role in intercepting pollutants, improving water quality and protecting water environment. The economic activities within the line were strictly prohibited. Compared to the protection line, the control line was much wider. Within the control line, the land use and social economic activities must be planned scientifically in order to make sure economic development without environment deterioration. In addition, based on the consideration of environment, flood control, regional economic development, riparian management and buffer zone construction etc, the method to determine protection line and control line was discussed. And then the Poyang Lake Basin was chosen as a case study area in this paper and some well results were obtained. It was indicated that the method of determining protection and control lines could help us to protect water environment under watershed scale effectively, and would provide a scientific reference for watershed plan and policy-making.