Abstract: Fuzzy clustering algorithm is widely applied in weather service，geology，pattern recognition and data mining．In this paper，fuzzy clustering was applied in core collection of crop and the traditional fluzzy clustering algorithm was improved．Based on similarity coefficient and distance coefficient, similarity degree has been presented which could describe not only the degree of value similarity，but also the degree of shape similarity．Replaced conventional similarity matrix by similarity degree matrix，the fuzzy clustering algorithm was effective．

Key words: fuzzy clustering, core collection, similarity degree