Screening candidate plants and revealing their stress-resistant mechanism are the key to phytoremediation. In order to reveal resistance and the physiological adaptation mechanism of Rhus chinensis to manganese (Mn) stress, the experiments on seed germination and seedling growth of R. chinensis were carried out in this study. We examined the germination and growth of R. chinensis seeds under different Mn²⁺ concentrations (0, 1, 5, 10, 15, 20 mmol/L), as well as the changes of physiological and biochemical characteristics in leaves of R. chinensis seedlings after 7, 15 and 30 days of manganese stress treatment. The results showed that: (1) with the increase of Mn²⁺ concentrations, the germination rate of R. chinensis seeds did not change significantly, ranging from 80.0% to 81.6%, while germination potential, germination index and vigor index increased at first and then decreased; other biomass indexes of R. chinensis seedlings showed a pattern of increased at first and then decreased. (2) The contents of chlorophyll a and chlorophyll b in leaves of R. chinensis seedlings increased at first and then decreased with the increase of Mn²⁺ stress concentration and the extension of stress time, and the carotenoid content showed a downward trend after 30 days of Mn stress. (3) After 7 days of Mn stress, with the increase of Mn²⁺ concentration, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in leaves of R. chinensis seedlings increased significantly (P<0.05); after 15 and 30 days of Mn stress, all activities of SOD, POD and CAT increased significantly (P<0.05) at low concentration, while at high concentration (15 and 20 mmol/L), the activities of POD and CAT decreased significantly (P<0.05). (4) After 7 days of Mn stress, the contents of soluble sugar, soluble protein and free proline in leaves of R. chinensis seedlings increased significantly (P<0.05) with the increase of Mn²⁺ concentration. After 15 and 30 days of Mn stress, the contents of soluble protein and free proline decreased significantly (P<0.05) when Mn²⁺ concentration was 20 mmol/L, but the soluble sugar did not decrease significantly. (5) With the increase of Mn²⁺ stress concentration and the extension of stress time, the content of malondialdehyde (MDA) in leaves of R. chinensis seedlings increased significantly (P<0.05) after 15 and 30 days of Mn stress. The results of this study show that R. chinensis has a strong ability to withstand manganese stress, which mainly responds to external manganese stress by enhancing the activity of antioxidant enzymes and accumulating a large number of osmotic adjustment substances in plants.