To study the triterpenoids from the roots of Rosa laevigata. The silica gel column chromatography was used to separate the chemical constituents from the roots of Rosa laevigata Michx. HPLC was used to analyze its purity, chemical and spectroscopy methods were used to determine their structures. 12 constituents were isolated and identified as(2R, 19R)methyl 2-acetyloxy-19- hydroxyl-3-oxo-urs-12-en-28-carboxylate(1), pomonic acid (2), 18, 19-seco, 2α, 3α-dihydroxy-19-oxo-urs-11, 13(18)-dien-28-oic acid(3), swinhoeic acid (4), myrianthic acid(5), 2α, 3β, 19α-trihydroxy-24-oxo-urs-12-en-oic acid (6), tormentic acid(7), arjunic acid (8), 1β-hydroxyeuscaphic acid(9), quadranoside Ⅷ (10), alpinoside(11), rubuside B (12). Compounds 1-4, 6, 9, 11-12 were obtained from this plant for the first time. Compounds 2-4, 6, 11-12 were obtained from the genus Rosa for the first time.