Abstract: The quality of Dendrobium species is depended on the contents of medicinal compositions, and selecting high quality Dendrobium is important for production and application. The polysaccharide and alkaloid contents were determined among 35 Dendrobium wild species and cultivars using the hot water extraction and acid dye colormetric method, respectively. The results showed that the polysaccharide contents of Dendrobium wild species and cultivars were between 2.0%-39.1% and 9.4%-23.7%, respectively, and the alkaloid contents of those were 0%-0.638% and 0.156%-0.308%, respectively. D.pendulum, D.officinale and D.devonianum had higher polysaccharide contents than others, while the alkaloid content of D.primulinum was significantly higher than that of others, followed by D. aphyllum, D.crepidatum and D.nobile. Meanwhile, Sect. Dendribium had the highest average polysaccharide content (23.2%) and alkaloid content (0.2%) in all samples, followed by cultivars (18.4% and 0.2%). The polysaccharide and alkaloid contents had significant differences among different Dendrobium wild species and cultivars, and selecting the proper Dendrobium should be in accord with objectives in practice.