The purpose of this study was to expand the utility of the Polygonum multiflorum. Also, we fermented P. multiflorum by mushroom mycelial, and analyzed for chemical compositions and biological active of fermented P. multiflorum root. The crude protein content did not show a significant difference between control and fermented P. multiflorum root, crude fat, ash and crude fiber content of fermented P. multiflorum root were lower than control. The content of soluble nitrogen free extract of P. multiflorum root was significantly higher than fermented P. multiflorum root. The major amino acids of P. multiflorum root were determined the arginine. The content of arginine and glutamic acid were 586.67 mg%, and 283.78 mg%, respectively. Sixteen kinds of amino acids were detected in fermented P. multiflorum root, and the major amino acids were determined the arginine and threonine. The total amino acid contents of control and fermented P. multiflorum root were 3,469.03 mg%, and 3,630 mg%, respectively. As the results of antioxidant activity test, the antioxidant capacity of fermented P. multiflorum had a higher than the control. As the mushroom fermentation progresses, it is confirmed that the amino acid content and antioxidant capacity were increased, and it is expected to develop the product using the fermented P. multiflorum using mushroom mycelials.