A lot of lakes or reservoirs have faced the problem of eutrophication in China, especially in Southern China. However, now it spreads to reservoirs and rivers in Northern China. An eutrophication control and algal bloom prevention system is outlined in this paper which based on the nature environment of the research waterbody and the eutrophied process control experiences. As a study case, Panjiakou Reservoir has the risk of eutrophication with a high concentration of Nitrogen and Phosphors. Eutrophication Control System was held which involved Eutrophication Control Subsystem, Monitoring Subsystem and Algal Bloom Prevention Subsystem. The risk water temperature is confirmed as 18°C and 25°C.