In this paper an approach to use qualitative information to infer unknown data by means of the fuzzy method is presented. The qualitative information are classified into tendency, relation, modification and quantified information which will be represented by the fuzzy set, fuzzy operation and fuzzy relation. Different fuzzy inference rules are discussed and the corresponding fuzzy relation equations are established to infer the unknown data. An practical example is presented to show how to use qualitative information to infer the vertical arm strength of women with help of the fuzzy method. >