Abstract: A gray nonlinear water environment management model was developed for comprehensive water environment improvement plan of Jialu River basin, Zhengzhou, which considered project construction, water environment improving strategy, construction and operation of sewage water treatment plants, and reservoirs regulation. The model was solved by the genetic algorithm(GA). The model took into account the operation optimization of sewage water treatment plants, the water supplement by south-to-north water diversion project, three ecological lakes and self-purifying capacities of the treated river reaches. By a more optimized and coordinated operation, higher attainment rate of multi-objects were achieved such as improvement of water ecology and water quality at a reasonable cost. The results show that the GA-based gray nonlinear programming has high potential applicability in regional water environment management.