With the continuous utilization and development of water resources, the problem of water pollution has become increasingly serious, and the ecological environment of river water has been gradually destroyed. Therefore, the control and protection of water pollution has gradually become the research focus of various research institutions. The study of the water environmental capacity of water bodies is of great significance for the prevention and control of water pollution. MIKEll, MIKE sHE and EC0 Lab were used to construct the coupling model of watershed hydrology, hydrodynamics, and water quality, to explore the migration and transformation of pollutants, and to further evaluate the effectiveness of river water quality improvement under different control measures. The research shows that the coupling model has good adaptability in the study area, the accuracy of hydrodynamic simulation is good, and the PBIAs of water quality simulation are all less than 40%. It is an improvement to reduce point source pollution of human rivers by improving the treatment rate of residents' domestic sewage and intercepting sewage at outlets. The key to the water quality of assessment sections, under the total control measures, 3 assessment sections c0D. NH, a N and TP annual average concentrations were reduced by 6.9l ~ 22.82, O. 66~2.70, O. 09—0.30 mg·L~, the decline rate is obvious, and gradually meet the water quality assessment standard of class V, and finally reach the level of class III~?.