Abstract: The alkali-extraction technology and antioxidant activity of total flavonoid from sedum aizoon L. were studied. The influences of the ratio of sedum aizoon L. to solvent, solvent pH value, extraction temperature and extraction time on extraction efficiency were investigated by single factor experiment, and the extraction parameters were optimized by orthogonal experiment. The results showed that the optimal parameters of extraction were as follow: the ratio of sedum aizoon L. to solvent was 1:10, solvent pH was 9, extraction temperature was 100℃ and extraction time was 6 h. Under these conditions, the yield of total flavonoid from sedum aizoon L.was 5.37 %. Total flavonoid from sedum aizoon L. has a obvious antioxidant activity, which could scavenge O2-·, OH· and DPPH· effectively, and the IC50 values were 0.013, 0.109 and 0.996 mg/mL, respectively. The results can provide a scientific basis for further development and utilization of sedum aizoon L.