Xinjiang lacks surface water source scriously, The underground water in many areas is brackish containing high salt or fluoride. Shixi oil field lies in the center of the desert. The underground water can't be drunk directly because many indexes of itsquality are beyond those required by the"Standard of drinking water" GB5749- 1985. They have successfully used a set of reverse osmosis unit( capacity 30 m³/ h) to solve this problem.After the treatment, the water quality meets the requirement of the standard of drinking water.