Abstract: Eight compounds were isolated from the aerial parts of Siegesbeckia orientalis L. and their structures were elucidated by spectroscopic methods(IR, EI-MS,¹³C-NMR, ¹H-NMR,¹H-¹H-COSY, ¹H-¹H-NOESY and ¹H-¹³C-COSY). Compounds I and II are new natural products and named siegesesteric acid(I) and siegesetheric acid(II), their structures were confirmed as ent-17-acetoxy-18-isobutyryloxy-16(α)-kauran-19-oic acid(I) and ent-17-ethoxy-16(α)-(-)-kauran-19-oic acid(II). The others were identified as known compounds: ent-16β, 17-dihydroxy-kauran-19-oic acid(III), kirenol(IV), β-sitosteryl glucoside(V), heneicosanol(VI), methyl arachidate(VII) and β-sitosterol(VIII). These compounds, except kirenol and β-sitosterol, were isolated for the first time from the title plant.