In order to investigate the effects of the joint operation of gates and pumps on the improvement of the water environment, using the central area of Suzhou City as an example, a one-dimensional hydrodynamic and water quality model for river networks, including 45 key hydraulic projects, was established based on measured data. The pollution sources were classified and calculated in detail. The measured water quality data were used to validate the model. The law of water quality change under the conditions of normal years and the current operation scheme was studied. The results show that the variations of concentrations of COD_Cr and NH⁺₄-N are negatively correlated with the water level, and the water quality in dry seasons is better in the northwest and worse in the southeast. Therefore, a scheme for reallocating the diverted water from the Xitang River using gates and pumps in the central area of the city is proposed to improve the water quality in dry seasons. The simulation results show that the water quality in most areas can reach a higher grade under the new operation scheme. The concentrations of pollutants in the monitoring sites decreased significantly, and the maximum reduction rate reached 49. 7%.