Abstract: 'Franch' plums were used as experimental material to elucidate the effects of short-term treatment with high concentration of carbon dioxide (CO₂) on post-harvest storage quality and antioxidant metabolism. The fruits were treated with 45%, 60%, and 75% CO₂ for 3 hours, and then stored at 1.0±0.5 ℃ for 49 days. The firmness, color, soluble solids content, titratable acid content, and indicators related to antioxidant metabolism of the plums were measured during cold storage. The results showed that short-term treatment with high concentration CO₂ can effectively maintain the firmness, color, soluble solids, and titratable acid content of plums, among which 60% CO₂ treatment showed the best effects in maintaining fruit quality. At the end of storage, the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR), and ascorbate peroxidase (APX) in the 60% CO₂ treatment group was 5.71%, 59.95%, 27.40%, 29.18%, and 45.00% (P<0.05) higher than those in control group, respectively. The content of ascorbic acid (AsA) and glutathione (GSH) was 1.42 and 1.23 times that of the control group, respectively. This increased the activity of antioxidant enzymes, maintained the content of ascorbic acid (AsA) and glutathione (GSH), reducing the production rate of superoxide anion (O₂⁻·), and delaying the accumulation of hydrogen peroxide (H₂O₂) content, malondialdehyde (MDA) content and the increase in cell membrane permeability. These results indicate that short-term treatment with high concentration CO₂ can enhance the antioxidant metabolism of plums during storage, thereby preserving fruit quality.