Abstract: Seven compounds were isolated from Astragalus membranaceus of northern shaanxi by silica gel and Sephadex LH-20 column chromatographies. Their chemical structures were identified on the basis of their physical and chemical properties. These compounds were elucidated as astragaloside Ⅳ (1), formononetin (2), calycosin (3), 1-(4-hydroxyphenyl)-4-(2, 4-hydroxyphenyl)-2-hydroxy-1, 4-but anedione (4), (E)-4-methylcinnamic acid (5), quercetin (6), and uridine (7). Compound 4 is a new compound and compound 5 was isolated from the plants of Astragalus Linn. for the first time. The results of in vitro antitumor activity assay showed that compound 4 could inhibit the proliferation of A549 with IC₅₀ values of 11.41 μmol·L^-1.