Abstract:Objective: To identify the botanical origin of the Guijiu in Shosoin of Japan from Tang Dynasty, and trace its medicinal history. Method: Anatomical characteristics of the underground parts of Guijiu in Shosoin were compared with those of Hosta plantaginea and H. ventricosa ,and research on the medicinal history of Guijiu was made based on its original identification results and escribes in herbals. Result and Conclusion: Guijiu in Shosoin of Japan was derived from the underground parts of H. plantaginea and is one of Guijiu used in Tang Dynasty and earlier on.