Abstract: The chemical constituents from Brassica rapa were identified by various chromatographic techniques including silica gel, reversed-phase silica gel, macroporous resin and Sephadex LH-20 column chromatography. Eight compounds were isolated from this plant. The isolated compounds were elucidated by physicochemical properties and spectroscopic methods, including extensive 1D, 2D-NMR, and HR-ESI-MS techniques. Compounds 1, 2 are new triterpenoids and 3-7 were isolated for the first time from Brassica rapa. The cytotoxic effect of compounds 1 and 2 were tested by MTT assay against five cancer cell lines. The result showed that all compounds exhibit growth inhibition for the cancer lines. Compound 1 has an IC₅₀ value of 5.87 μmol·L^-1 for growth inhibition of leukemia cell line HL-60, and IC₅₀ value for compound 2 was 10.32 μmol·L^-1.