Abstract: The paper makes census and analyses of kuitun city in ground water environmental background values, and applying to the theory and methords of fuzzy mathematics, according to the practical dates of evaluating factors in water sample analyses, utilizing appropriate judging rules in different contribution envirommental quality levels, considering hisce evaluating factors different contribution to the water environmental quality, and on he basis of passing fuzzy judgement on single factor, properly and reasonably pass synhetic judgement on the degree that the water samples are subordinated to different ground vater enviromental grades.