There are multi-aspects influence of soil and water loss on water quality of reservoir. The results have showed that the most important effect of soil and water loss on Qinglinjing reservoir is as followes: The turbidness index of water body shows direct ratio relation with intensity of rainfall. When nutrient salt is brought by soil and water loss into water body, the water quality is near nurtured level, while in severe area of soil and water loss, shows middle-rich nurtured level, the amount of microorganizm increase obviously. The whole water quality shows a tendency to deteriorating.