Abstract: Fuzzy clustering analysis is used to classify the different samples of the soil resources of the loess plateau, in accordance with their physicochemical properties.
On this basis, then, the samples are arranged in order of quality, using grade-2 Fuzzy synthetical judgement.It is shown that the Fuzzy approach in the quantitative research of soil, is far better than any other quantitative approach. It can provide a reliable scientific basis for the protection and exploitation of soil resources. Therefore it is regarded as a basic approach to the appraisal of soil quality.

Key words: Fuzzy clustering analysis, quantitative research of soil, grade-2 Fuzzy synthetical judgement, appraisal of soil quality