The polysaccharide content was determined by the modified phenol-sulfuric acid method (Luo et al., 2010). Dry powder ofDendrobium nobile (0.5 g) was placed in a 100mL round bottom flask, added 50mL 80% ethanol heated at 80℃ reflux for 1h. Then the solution was filtered and the filtrate was discarded. Next the filter residue was placed in the round bottom flask again. 50 mL of distilled water was added, and the mixture was heated to reflux at 100℃ for 2 hours, and the filtrate was taken, and the volume was adjusted to 50 mL to obtain a polysaccharide extract. The polysaccharide content was determined by the phenol-sulfuric acid method. The standard curve is made with glucose.