Catalase C (CatC), as an important antioxidant enzyme, plays important roles in rice development and stress response. In order to explore the function and mechanism of CatC involved in the response to salt stress in rice, we constructed OsCatC overexpressing transgenic rice plants, and analyzed their salt tolerance and related physiology in this study. The results demonstrated that: (1) an expression vector pCUbi1390OsCatCFlag was successfully constructed, thirty independent transgenic lines (T₀) were obtained via Agrobacteriummediated callus transformation, and two OsCatC overexpressing transgenic lines (OE10, OE18) were identified by Western blot analysis of T₁ seedlings. Meanwhile, qRTPCR analysis revealed that the transcriptional levels of OsCatC in OE10 and OE18 were significantly higher than that of wildtype (WT) plants, indicating that OsCatC was successfully overexpressed and normally translated into the fusion protein CatCFlag in the transgenic lines (OE10, OE18). (2) Under normal hydroponic conditions, no significant difference was observed in the seedling growth between WT and transgenic lines OE10 and OE18, while treated with 200 mmol·L^-1 NaCl for 7 d and recovered for 10 d, the survival rates of OE10 and OE18 seedlings remained 20%-25%, whereas the majority of WT seedlings dried up and died, and the survival rate was only about 5%. (3) Compared with WT, OsCatC overexpressing seedlings (OE10, OE18) exhibited higher tolerance to salt stress with lower relative electrolyte leakage, malondialdehyde (MDA) and H₂O₂ contents, and their catalase activities were markedly increased. The growth inhibition degree of OE10 and OE18 was significantly lower than that of WT, and their seedling length was markedly higher than that of WT after treatment with 4 μmol·L^-1 methylviolet (MV) for 7 d, indicating that the transgenic lines had a stronger tolerance to oxidative stress. This study discovered that CatC reduces oxidative damage mainly by degrading the excessive accumulation of H₂O₂ under salt stress, thereby improving the salt tolerance of rice, and further verified that overexpression of OsCatC can enhance the tolerance to salt stress in rice, and that OsCatC is a promising candidate gene for the cultivation of salttolerant rice.