[Objective] To study the surface water quality changes of Xinzhou section of Hutuo River in past eight years and discuss the natural

social and economic factors that affect the water quality changes.[Methods] The water quality monitoring data and relative natural social and economic statistical data from 2004 to 2011 were used and the organic pollution comprehensive index method was adopt.[Results] (1) The surface water quality changes of Xinzhou section can be divided into consistently deteriorating and rapidly improving periods. The turning point of the water quality change was in 2007. And the organic pollution indexes(T) of the two periods were 5.51 and 2.85. (2) In terms of natural factors

the river water

precipitation were negatively correlated with the water quality

and the correlation coefficient were 0.675 and 0.532(p<0.01).The effect of river water and precipitation on the river water quality improvement was limited. For the social and economic factors

the water quality deterioration was mainly related to the industrial waste emissions

the amount of chemical fertilizers

the sewage emissions and the sewage treatment capacity. The correlative coefficient were 0.689(p<0.01)

0.633(p<0.01)

0.465(p<0.05)

0.905(p<0.01).[Conclusion] Although the sewage surpassed the industrial waste water discharge after 2009

the standard operation of sewage treatment plant further improved the river water quality. The sewage rate was the premise of continuous improvement to ensure water quality in the future at the region. The economic development and urbanization did not bring pressure to the water quality. And the economic development became the positive power.