OBJECTIVE： To determine quality indexes of Hejiang Dendrobium nobile at different harvesting time and months， and to provide scientific reference for reasonable harvesting period of Hejiang D. nobile. METHODS： The stem of annual， biennial and triennial D. nobile were collected. The drying rate， the contents of polysaccharides （colorimetry）， dendrobine （GC） and total alkaloids （colorimetry）， effective component total rate （dendrobine×drying rate） were measured. Biennial D. nobile were collected in autumn and winter （Oct. of the second year-Mar. of the third year， 15th day a month） to determine drying rate， the contents of polysaccharides and dendrobine. RESULTS： The drying rate， the contents of polysaccharides and effective component total rate were higher than annual and triennial D. nobile. The content of total alkaloids and dendrobine were in descending order： annual D. nobile （0.52％， 0.48％）＞biennial D. nobile（0.48％， 0.44％）＞triennial D. nobile （0.32％， 0.22％）. From Oct. of the second year to Mar. of the third year， the drying rate of biennial D. nobile was increasing month by month； the contents of polysaccharides and dendrobine increased firstly and then decreased； the content of polysaccharide was the highest in Feb. （17.32％）， and the content of dendrobine reached the highest level in Dec. （0.51％）.  CONCLUSIONS： The optimal harvesting period is biennial Hejiang D. nobile in Dec. and Jan. （third years before flowering）， considering flowering characteristics， drying rate， the contents of polysaccharide and dendrobine.