Based on environmental pollution index, a synthesized method, fuzzy relation analysis (FRC), is obtained by combining fuzzy comprehensive evaluation and gray relation method,and it is applied to air environmental quality assessment.

By analyzing the defects of all kinds of aridity index accepted internationally that listed in the articles of WMO and Heim of the Unite States,we get the grey connected analytic method of the arid degree which based on the theory of grey system to used for evaluating a arid degree.