Abstract: The influencing factors on gastrodin content in the crude materials of Gastrodia elata were investigated by HPLC analysis . The results indicated that the preparing method of post harvest is a more important factor for the gastrodin content, comparing to those brought about by the growing areas and herbal varieties . Among the different processing methods, steaming produced the most impact effect on the increment of gastrodin in the herbal material . The possible mechanism of gastrodin formation during the crude process was also discussed.

Key words: Gastrodia elata