Abstract: To study the efficient reduction of pollutants in inflow rivers, this paper took the Tiegang Reservoir in Bao’an District of Shenzhen as the research object, combined with the water quality of inflow rivers and the implementation status of the existing water quality improvement projects, proposed a process of "regulation and storage + treatment + transferring" to treat non-point source pollution in the basin, and analyzed the treatment results of this process. The results showed that the pollutant concentration of the four rivers flowing into the Tiegang Reservoir exceeded the Class Ⅴ in Surface Water Quality Standard of China (GB 3838—2002),and in the river basin, the non-point source pollution of 65000 m³ of initial rainfall water had not been resolved. The project set up six storage tanks to collect the 65000 m³ of initial rainfall water. After storage and regulation, the process of "A²/O biological reaction tank + high-density sedimentation tank + modular open channel ultraviolet disinfection device" was adopted for treatment; after treatment, the removal rate of COD in the initial rain reached 86.9%, and the removal rates of BOD₅, ammonia nitrogen, total nitrogen, and total phosphorus all reached more than 94%. The water quality met the class Ⅳ surface water quality standard, and could directly feed the reservoir inflow river.