This study explores the relationships between knowledge and classification. Classification schemes have properties that show the representation of entities and relationships in structures that reflect knowledge being classified. Four representative classifying methods. i. e. hierarchies, trees, paradigms, and faceted analysis those brings new knowledge are analyzed and those strengths and weaknesses are described. Based upon the analysis, the links between knowledge and classification are verified. Finally a better way of representing knowledge structure through classification schemes in the future is suggested.