The quality of drinking water for human and animals affected by soil and water loss in Yunnan province is investigated and analysed.Taking Dachongqing reservoir as an example, because of soil and water loss, there are a lot of harmful chemistry and germs in soil going into reservoir with runoff, the quality of water in reservoir was changed. If the water is not handed by a special process, it is not good for human and animals to drink. There are various kinds of factors that affect the water quality by soil and water loss in this reservoir. People must notice this problem, when the poor water is supplied for human and animals in countryside.