Effects of short-term high CO2 treatment at different concentrations (30% and 40% and 50% ) on the senescence of postharvest tumorous stem mustard were investigated. Fresh tumorous stem mustards were treated with mixed gas of CO2(30%)+N2(70%), CO2(40%)+N2(60%) and CO2(50%)+N2(50%) respectively after pre-cooling, using ambient atmosphere as the control, and stored in Climate box at (4 ± 1) ℃ and 90%~95% relative humidity (RH) for 48 h. After short-term CO2 treatment, tumorous stem mustards were stored in polyethylene package with a thickness of 0.03 mm at (4 ± 1) ℃ and 90% ~95% RH, and the respiration intensity, activity of senescence-related enzyme, Vitamin C content were determined at regular time interval during the storage. The experimental results showed that short-term high CO2 treatment at the concentrations of 30% and 40% and 50% could significantly reduce the respiration intensity of tumorous stem mustards. Short-term high CO2 at the concentrations of 30% and 40% could keep higher activities of superoxide dismutase (SOD), catalase (CAT) , and inhibit the increase of peroxidase (POD) and polyphenol oxidase (PPO) activities as well as the decline of Vitamin C content in peel of tumorous stem mustards. The effect of short-term CO2 at the concentrations of 40% was the most remarkable. However, short-term high CO2 treatment could not obviously affect the senescence-related indicators of tumorous stem mustard pulp. Short-term high CO2 at the concentrations of 40% could delay the senescence progress of postharvest tumorous stem mustard.