To analyze the pollution and environment condition of Lishui Fangbian Reservoir, the indexes, including COD, TN, TP and the content of chlorophyll, were investigated in this research. It was found that non-point source pollution with the agricultural runoff was the main pollution source. The water quality in the reservoir belonged to grade IV, and the main pollutants in the water source are TP and TN. Through an exponential analysis of a large number of data we found that the water quality is at the best condition with the status of oligotrophy to low-medium trophy during normal water season, while it was at the worst condition with oligotrophic to medium trophic level during high water season. At the low water season, the water exhibited a mild eutrophication trend. With respect to the sediment, the heavy metal pollution was at the low level of risk, the sediment of the whole Fangbian reservoir belongs to the nutrient salt polluted sediment, and it was seriously polluted by organics that might need further dredging. This study would provide a guidance for the prevention and controlling of eutrophication in the water reservoir.