Objective:To study the chemical constituents of Polygonum capitatum. Methods:Isolation and purification of the chemical constituents were carried out repeatedly by silica gel column and Sephadex gel column chromatography. The structures of compounds were identified by physical-chemical methods and spectral data. Results:Fourteen compounds were identified from the petroleum ether fraction of P. capitatum:tricosanol (Ⅰ),pentacosanol (Ⅱ),docosanoic acid (Ⅲ),lignoceric acid (Ⅳ),hexadecanoic-2,3-dihydroxy-propyleste (Ⅴ),docosanoic-2,3-dihydroxypropyleste (Ⅵ),oleanolic acid (Ⅶ),ursolic acid (Ⅷ),octacosa-1,27-diene (Ⅸ),docosyl ferulate (Ⅹ),β-sitosterol (Ⅺ),tricosane (Ⅻ),hexadecanoic acid (),and linoleic acid (). Conclusion:Compounds Ⅰ-Ⅹ are obtained from P. capitatum for the first time. Compounds Ⅸ and Ⅹare obtained from Polygonum for the first time.