Object To study the effect of plant growth regulator on medicinal constituents of Dendrobrium nobile Lindl Methods The root of D nobile was treated by immersing in solutions of plant growth regulator 6 BA and GA 3 Results and Conclusion Both plant growth regulator at certain concentration, resulted in an increase of total soluble sugar content, but without effect on the content of dendrobine GA 3 can significantly elevate the content of total alkaloid in D nobile