The contents of soluble proteins and chlorophyll of the detached leaves of rice treated by triadimefon(mass concentration=20 mg/L) increased. The results indicated that triadimefon retarded the senescence of rice leaves. During the senescence of detached rice leaves, both the activities of superoxide dismutase and catalase and the contents of ascorbic acid and reduced gluthione decreased, which was inhibited by triadimefon. These results suggested that triadimefon enhanced the protective ability against enhanced lipid peroxidation.