Through the contrast analysis on the water quality of mainstream and its tributaries,the mainstream and nearby underground water of Kuye River(Shaanxi section),the sewage discharge along the Kuye River(Shaanxi section) and the reasons of water quality variation were discussed.It considers that the water quality change of Kuye River(Shaanxi section) is related to the joining of tributary water and groundwater replenishment to the river.And the sewage flowing into the Kuye River(Shaanxi section) directly is t...