Abstract： Object To study the chemical constituents of the root of traditional Chinese medicine"Yuanzhi" (Polygala tenuifolia Willd. ). Methods Seperation and purification were performed on silicagel, Sephadex LH-20 and ODS CC. Their structures were established on the basis of physicochemical andspectral analysis. Results Five compounds were isolated and identified as tenuifoliside B ( Ⅰ ), methyl 3,4, 5-trimethoxycinnamate ( Ⅱ ), polygalaxanthone Ⅲ (Ⅲ ), 7-O-methylmangiferin ( Ⅳ ) and lancerin( Ⅴ ), respectively. Conclusion Compounds Ⅱ and Ⅳ were isolated from the plant of Polygala L. for thefirst time and compound V was isolated from P. tenuifolia for the first time.