The photosynthetic pigment,lipid peroxidation and anti-oxidation enzymes in the leaf of Pleioblastus kongosanensis were analyzed under the stress of elevated concentration of CO₂ (700 μmol·mol^-1) and O₃ (100 nmol·mol^-1) in open-top chambers (OTCs).After samples treated for 103 days and compared to the control,the results showed that:(1)In the elevated O₃ treatment groups,the contents of Chl a,Chl b,total Chl and the ratio of Chl a/Chl b,Chl/Car,the activities of SOD,POD and CAT were decreased significantly,while the contents of O^-·₂,MDA,Car,relative electrical conductivity and activity of APX were increased significantly;(2)In the elevated CO₂ treatment groups,the contents of Chl a,Chl b,total Chl and the ratio of Chl/Car were increased significantly,and the ratio of Chl a/Chl b,contents of O^-·₂ and MDA,activities of SOD,POD,CAT,APX were decreased significantly and relative electrical conductivity,content of Car had no significant difference;(3)In the elevated O₂ and CO₂ combined treatments,except Chl/Car ratio and CAT activity were decreased significantly,other physiological indicators had no significant differences.The results showed that the activities of anti-oxidation were significantly decreased,at the same time the O₃ and malondialdehyde contents were increased significantly by elevated O₃,so that the cell membrane structure was damaged seriously which represents injured effects to P.kongosanensis.Reactive oxygen species were decreased significantly by elevated CO₂,which presents protective efficacy on P.kongosanensis.In combined stresses of elevated CO₂ and O₃,the leaves of P.kongosanensis could maintain high levels of photosynthetic pigment content and antioxidant activities to effectively regulate reactive oxygen species generation and clearing balance,indicating that elevated CO₂ could ameliorate the oxidative stress in certain degree.