To study the polyphenols from Dendrobium loddigesii and their biological activities, the 80% acetone extract from D. loddigesii was isolated and purified by chromatography techniques; the structures of obtained compounds were identified with spectroscopic techniques; the antioxidative, α-glucosidase inhibitory and antiinflammatory activities of compounds were evaluated. Fifteen compounds were isolated and identified as chrysotoxol A (1), neoechinulin A (2), 3,6,9trihydroxy-3,4-dihydroanthracen-1(2H)-one (3), 4,4′=dihydroxyl-3,5-dimethoxylbibenzyl (4), naringenin (5), 5,4′-dihydroxy-7,3′,5′-trimethoxyflavanone (6), 5,7,4′-trihydroxy-3′,5′-dimethoxyflavanone (7), batatasin-III (8), 3,3′,5-trihydroxybibenzyl (9), trigonopol B (10), syringaresinol (11), 2,4,7-trihydroxyl-9,10dihydrophenanthrene (12), loddigesiinol B (13), loddigesiinol I (14), loddigesiinol J (15),respectively. Compounds 1-11 among them were isolated from D. loddigesii for the first time. The biological activities of compounds 1-4, 6, 7 and 12 were evaluated for the first time under trial conditions. It was reported for the first time that compounds 1, 3 and 12 had a strong antioxidant activity, compounds 1 and 9 showed a strong α-glucosidase inhibitory activity, and compounds 1, 12, 14 and 15 had a strong anti-inflammatory activity.