Abstract: In order to evaluate the antioxidant activities and the major chemical constituents of Rosa sterilis, the antioxidant activities of the juice extract and pomace extract of title plant were evaluated by DPPH and ABTS free radical scavenging assays, and the contents of total polyphenols, total flavonoids and total triterpenoids in the juice and pomace were determined by ultraviolet spectrophotometry, respectively. The results showed that the SC₅₀ values of the juice extract against DPPH and ABTS free radicals were (17.58±0.48) μg/mL and (56.26±3.07) μg/mL, and the SC₅₀ values for the pomace extract against DPPH and ABTS free radicals were (45.38±0.68) μg/mL and (101.67±1.15) μg/mL, respectively, indicated that the in vitro antioxidant activity of the juice extracts is stronger than those of the Vc and pomace extract. The ROS scavenging rates of juice and pomace extracts were (84.80±3.40) % and (83.80±3.60) %, respectively, indicated that the in vivo antioxidant activity of 2 extracts was similar and stronger than that of the positive control GSH. The results also showed that the contents of total polyphenols, total flavonoids and total triterpenoids were (32.81±0.19) mg/g, (29.62±0.06) mg/g and (61.88±0.62) mg/g in the juice, and (21.66±0.29) mg/g, (12.11±0.05) mg/g and (15.16±0.22) mg/g in the pomace, respectively, indicated the contents of the major chemical constituents in the juice is higher than those of the pomace, which with a positive correlation to their antioxidant activities.