Abstract: On basis of the field monitoring data obtained from 2010 to 2015, quality of water environment in the Xiaoqing River estuary was assessed and the flux variations of its major pollutants were explored systematically. The results showed that average concentrations of total phosphorus (TP), chemical oxygen demand (COD) and petroleum were all beyond the quality standards for Class Ⅲ water, according to Environmental Quality Standards for Surface Water (GB3838-2002). In Xiaoqing River estuary, the average comprehensive pollution index was 16.79 and the average pollution index was 1.53. Moreover, the major two pollutants of Xiaoqing River estuary were petroleum and COD, and the quality of water environmenthad been generally improved during 2010 to 2015. The average total amount of major pollutants discharge into the sea from the Xiaoqing River was 159766 t, in which COD played the leading role. Sources of pollutants in the Xiaoqing River included point pollution and non-point pollution. The point source pollution came from coastal sewage outfall of Xiaoqing River, while the non-point pollution came from chemical fertilizers in agriculture.