The pollution of Tarim River may have negative effects on ecosystem stability and sustainable de-velopment in the area of the middle and lower reaches. Using the actual measured data from Longkou and Shi daqiao observation stations on Aksu River and the Alar and 14 Tuan observation stations on the main stream of Tarim River in 2001-2005

authors carry out a research on water quality assessment of Tarim River based on the statistic software STATISTICA

principal component factor analyses

and water pollutant synthesis index methods. The result shows that water quality of the Longkou and Xidaqiao observation stations be-longs to first degree(cleanness) water

and the water quality of Alar and 14 Tuan observation stations be-longs to fourth degree(middle pollution) and fifth degree(serious pollution ) water

respectively. The major pollutants in Tarim River are chlorides

total hardness

mineralization degree

sulphate

fluoride

etc.