Based on the case study of Shangdong Province, the relationship between economic development and water environment pollution is studied. The concept of coupling in physics is introduced into the studies on the correlation between economic index GDP and monitoring indices of water pollution. By establishing a coupled model for the degree of correlation between GDP and water pollution indices, the correlation between them can be obtained, and the coupling mechanism between GDP and water pollution indices is evaluated. The calculated results show that there is a coupling relationship among GDP, domestic sewage and industrial sewage, and the coupling between GDP and the domestic wastewater is higher than that between GDP and industrial wastewater. On this basis, some suggestions and measures put forward to alleviate the pollution process of domestic sewage and improve the water environment so as to achieve the harmonious development of regional economy and eco-environmental protection.