Abstract: Since the beginning of the 1960s, some endemic diseases, such as endemic diarrhoea, potassium-deficiency in blood and endemic sterility, had been found in Kashi Plain in Xingjiang. These diseases severely threaten human health. It is considered that bad drinking water relates to these diseases. Inhabitants in this area have a fear of the drinking water. According to the above condition, the author made a research on hydro-geochemical characteristic. In late of the 1980s, 22 common elements and 24 trace elements of 355 water samples were analysed. Based on the analysis the evaluating grades( I-V)of water quality were formulated, and methods of fuzzy mathematics and synthesis index are used to evaluate the quality of drinking water and irrigating water. The results show that the healthy drinking water( I-Ⅲ) made up 68. 16% of the whole water samples, the unhealthy water made up 31. 84% of the whole water samples and moderate irrigating water made up 83% of the whole water samples.The research plays an important roly in rational development and utilization of water resources, assurance of human health and improvement of agricultural production, and obvious social, economic and environmental effects had been obtained.