The main problems and changing trends of water environment in Xinjiang Wei Autonomous Region,as well as their causes,are analyzed by Ridit analysis method and other qualitative and quantitative methods based on the water monitoring data and economical data from 2001-2006.Results show that water quality of rivers in Xinjiang is in slight pollution.Water pollution in the north is more serious than that in the south.Water quality of the rivers far from urban areas is better than that through urban construction areas.The changing trends of water quality of rivers are stable.Water qualities of lakes and reservoirs are in medium pollution.Water quality of lakes is better than that of reservoirs.The changing trends of the water qualities of lakes and reservoirs are stable.Water quality of drinking water sources are good basically and its changing trend is stable.Ground water quality in Urumqi is in the degree of Ⅳ—Ⅴ and its changing trend is stable.The main causes leading to the water problems in Xinjiang are the heavy industrial structure,rapid growth economy,weak urban infrastructure,heavy pollution in rural areas,and poor protection of drinking water sources.