Abstract: AIM To separate, identify and quantify multi components in complex traditional Chinese medicine (TCM) Astragalus membranaceus by unified analysis for systematic study of its relative contents. METHODS The analytical method was reverse phase HPLC/photodiode array detector. Based on the comparison of UV spectra, software of UV database to assist recognition has been established. Key components have been found and recognized in two reference Astragalus membranaceus and three samples from different sources. With the unified analytical project, relative peak heights of key components were recognized and contrasted. RESULTS The water soluble components can be separated by solvent system A, a gradient program with mobile phase of methanol water. The liposoluble components can be separated with the solvent system B, a gradient program of mobile phase of 2-propanol-acetonitrile-water. UV detection wavelength was set at 202 nm and the flow rate was 1 mL·min^-1 on a Hypersil ODS column. Twenty nine components in the four Astragalus membranaceus were recognized using characteristic parameters of chromatography and UV spectroscopy. All of the 29 key components in two reference samples and three samples from different sources were shown in their chromatograms to be the same. The concentrations of some the key components in different samples were similar while those of the others were different. The chromatographic peaks of the reference Astragalus membranaceus and two samples were matched with each other. Many different fingerprints were found and differences were shown on their chromatograms. Not only there were differences among three samples from different source, but also there were differences in the two reference samples. CONCLUSION To find out the key components and recognize them are the basis of quantitative recognition and are very useful when standards are not available. The method of multi component quantitative recognition in Astragalus membranaceus was developed. The method is convenient and reproducible. It can be widely used for the quality control of the Astragalus membranaceus .