Abstract: To research the difference of chemical components in different origins of Dendrobium huoshanense C.Z.Tang et S.J.Cheng,Dendrobium officinale Kimura et Migo and Dendrobium moniliforme (Linn.) Sw.and to provide references for protection and utilization of Dendrobium plants.The fresh collected Dendrobium samples were washed thoroughly in water and then freezedried by a MicroModulyo lyophilizer,powdered in a blender and extracted with ultrasonic by methanol for 1.0 h.Then the filtrate was freezedried to remove the methanol and the residues was redissolved in water and extracted by nhexane.The nhexane extraction was remove for further GCMS analysis.The isolated chemicals were identified by comparing their RM and KI values and the known chemical in the NIST2010 library.The quantitative analysis of each component can be directly calculated by the overall volume integration.At last,a PCA analysis was applied to investigate the main variation of chemical in the six Dendrobium samples.Total 109 chemicals were isolated and 72 of them were identified.The main compositions in the six Dendrobiums were alkane,ester,alcohols,phenol,terpenes and sterols.The compositions and contents were different in different origins of D.huoshanense,D.officinale and D.moniliforme.The PCA analysis resulted that the first three principal components explained 92.3% of the variance of the data and the loading plot of the three first components showed a strong relationship between seventeen major compounds 7、9、15、17、37、43、46、57、65、72、80、88、91、96、98、101、106.The chemical compositions were different among different origins of D.huoshanense,D.officinale and D.moniliforme.The research provides a scientific basis for the further development and utilization of Dendrobium resources.

Key words: Dendrobium huoshanense, Dendrobium henanense,  Dendrobium officinale, Dendrobium moniliforme, GCMS；principal component analysis