Application of fresh herbs is a kind of special forms of traditional Chinese medicine. In China, there is a long and rich experience in clinical application of fresh herbs. Many studies showed that the efficacy of fresh herbs was better than that of dried herbs, but the further study about the difference of their chemical composition, effective components and the overall material basis were few. In this paper, the ideas and methods to study on material basis of the fresh herbs by comparing the difference of the fresh and dry herbs in medicine chemical composition and pharmacological activity of effective components with modern advanced separation, analysis and screening technology under the "Constituent structure theory" were proposed. It was an effectual method for studying on the reasonable development of Chinese medicine and fresh herbs resources.