To investigate the chemical constituents from the Brassica rapa L. ssp. pekinensis (Cruciferae).The constituents from the 95% ethanol extract of Brassica rapa L. ssp. pekinensis were separated and purified by silica gel chromatography,Sephadex LH-20,semi-preparative high performance liquid phase,crystallization,recrystallization technologies.The structures of isolated compounds were elucidated by physicochemical properties and spectral data analysis.Fifteen compounds were isolated and purified.They were identified as β-sitosterol(1),5-hydroxymethylfurfural (2),n-butyl-β-D-fructopyranoside (3),(6S,9S)-roseoside(4),uridine(5),succinate(6),methyl succinate(7),p-hydroxycinnamic acid(8),ethyl-β-D-glucopyranoside (9),butyl pyroglutamate(10),cyclo (Pro-Leu)(11),cyclo(Tyr-Leu)(12),1-chlorohexadecane(13),oleamide(14),stigmastane-3,6-dionez(15).Compounds 3 and 6-15 are obtained from the plants of Brassicas.for the first time,and compound 1,3-15 is isolated from Brassica rapa L. ssp. pekinensis for the first time.The effect of the compound 3 on inhibiting the growth of laryngeal carcinoma Hep-2 cells in vitro was examined by MTT.