Caulis Dendrobii (Shihu in Chinese), a well-known traditional Chinese medicine (TCM) recorded as first grade in Shen Nong Ben Cao Jing, is used for treatment of asthenia pyrosyndrome, dim vision and retching, etc. According to Chinese Pharmacopoeia (2005 edition), the fresh or dried stems from Dendrobium nobile Lindl., D. officinale Wall. ex Lindl., D. fimbriatum Hook. var. oculatum Hook. and the allied species are all used as Shihu. The active components exist in Dendrobium are very complex, which mainly include polysaccharides, phenols, alkaloids, coumarins and terpenes. Therefore, quality control is very important to ensure the safety and efficacy of Dendrobium. However, current methods usually focus on single compound or one type of componets. In addition, only a few reports concerned the analysis of polysaccharides. In present study, accurate, quick and convenient methods have been developed for simultaneous determination of three types of active micro-molecular compounds and discrimination of polysaccharides from different Dendrobium, respectively. The thesis consists of five chapters. Chapter 1 briefly reviewed the advance on the chemitry and quality control of Dendrobium. In Chapter 2, the parameters of pressurized liquid extraction (PLE) including solvent type, extraction temperature, static extraction time and particle size were optimized using univariate approach. Followed by that, an Ultra performance liquid chromatography-photo diode array (UPLC-PDA) method has been developed for fast determination of five components including one coumarin (scoparone), two alkaloids (dendrobine and dendronobiline A) and two bibenzyl (gigantol and moscatilin) in 21 samples from 15 Dendrobium species. The results showed that the contents of investigated compounds were greatly varied in different species or locations of Dendrobium. Gigantol and moscatilin were widely existed in Dendrobium species though their amounts were significantly different. Scoparone and dendrobine were the characteristic components of D. thyrsiflorum and D. nobile, respectively. Dendronobiline A was not detected in any Dendrobium species. In Chapter 3, a method using PLE and UPLC-PDA was developed for investigating chromatographic fingerprint of 18 samples from 15 Dendrobium species. Though the common compounds such as moscatilin and gigantol could be found in different species of Dendrobium, there were notable distinctions in different species of Dendrobium, even the same species from different locations. In Chapter 4, a novel method, saccharides mapping, based on enzymatic (carbohydrase) digestion and subsequent chromatographic analysis of enzymatic hydrolysate, was successfully applied to discriminate crude polysaccharides from different Dendrobium species, as well as the same species from different locations. According to the digestion response of the selected carbohydrases, polysaccharides from D. fimbriatum (Yunnan) and D. nobile (Guizhou) could be discriminated out of 8 investigated polysaccharides. Subsequently, the remained six polysaccharides, which could be correspondingly divided into three groups according to their enzymatic hydrolysis characteristics, i.e., the polysaccharides obtained from D. officinale (Yunnan) and D. huoshanense (Anhui), D. officinale (Anhui) and D. chrysanthum (Yunnan), as well as D. officinale (Zhejiang) and D. nobile (Yunnan). They could be distinguished by chracteristic saccharide maps of arabinanase, cellulose or pectinase hydrolysates. Chapter 5 was a summary of this study.