This study aims to investigate the antioxidant and hepatoprotective activities of different polar extraction parts of Brassica rapa L. in vitro and in vivo, and to preliminarily evaluate its safety, so as to screen the best active parts and provide scientific reference for the development and utilization of B. rapa. DPPH, ABTS free radical scavenging ability and total antioxidant capacity (T-AOC) were detected; a mouse model of liver injury induced by carbon tetrachloride (CCl₄, 0.15%,0.06 mL/10 g) was established. The activities of aspartate transaminase (AST) and alanine aminotransferase (ALT) in serum and superoxide dsmutase (SOD) and glutathione peroxidase (GSH-Px) in liver homogenate were determined, and the antioxidant and hepatoprotective activities of different polar extracts of B. rapa in vitro and in vivo were investigated. The signs and death of mice were observed continuously for 14 days by giving the extract solution of different polar extraction parts of mice. At the end of the experiment, the weight gain of mice was counted, and the organs were dissected and observed to evaluate their toxic reactions. The results showed that the order of IC₅₀ values of DPPH and ABTS free radical scavenging rates of different polar extraction parts was: water suspension extraction part > petroleum ether extraction part > n-butanol extraction part > ethyl acetate extraction part. Ferric reducing ability of plasma method was used to determine the T-AOC of ethyl acetate and n-butanol extracts. The results of in vivo experiments showed that the ethyl acetate and n-butanol extracts could significantly reduce the levels of AST and ALT in the serum of mice with liver injury induced by CCl₄ (P < 0.05,P < 0.01), and significantly increase the activities of SOD and GSH-Px in mice. Compared with the model group, there was a significant difference (P < 0.05). The pathological results showed that the positive drug (bifendate dropping pills), ethyl acetate and n-butanol extracts could effectively reduce the acute liver injury induced by CCl₄ in mice. After mice were given different polar extraction parts of B. rapa, no acute toxicity was observed, suggesting that it was safe and non-toxic. In summary, among the different polar extracts of B. rapa, n-butanol and ethyl acetate extracts have better antioxidant activity in vitro, and have good antioxidant and liver protection effects in vivo and in vitro.