Abstract: Mushrooms( Agaricus bisporus) were dipped for short time in 0.3 MPa CO₂,then stored at 4 ℃ for 8 d.Changes of the browning,membrane permeability,lipid peroxidation,reactive oxygen species,and free radical scavenging enzyme activity in the mushroom tissue were measured. The results indicated that the short- term preservation effect of 0.3 MPa CO₂ treatment on A. bisporus was not ideal. Browning,relative leakage rate,the production rate of O₂^-·and the contents of MDA and H₂O₂ of A.bisporus dipped for short time in 0.3 MPa CO₂,were increased with lower CAT and SOD activity during the first four days.However,the short- time high- pressure CO₂ treatment showed the preservation effect on A. bisporus as time prolonged. In the late storage,0.3 MPa CO₂ treatment inhibited the browning and decreased the relative leakage rate,the production rate of O₂^-·,and the contents of MDA and H₂O₂. Moreover,the corresponding oxygen radical scavenging enzyme activities including CAT and SOD in mushroom dipped for short time in 0.3 MPa CO₂ were higher than those in the control.In addition,0.3 MPa CO₂ treatment could reduce the loss of total phenolic and ascorbic acid of A.bisporus,and then inhibit the browning.