Abstract. Based on the twenty years’ hydrologic data and water quality materials from the year 2005 to 2010, this article studies the water environment changes of reservoir type water source and the water quality protection countermeasures. Through the analysis, it founds that, with the increase of the rainfall, voluminous non-point source pollution was brought to water. The increase of rainfall runoff influences differently to the reservoir's major pollutants -TN and TP. The increase of the rainfall runoff has a dilute effect on TN; with the increase of the rainfall runoff, the TP threshold will increase.