Ultrasonic-assisted extraction of total phenolic acid from Sedum aizoon L. was carried out. The extraction rate was determined by spectrophotometer. The effects of extraction time, temperature, ratio of material to liquid and concentration of ethanol on the extraction rate were discussed. On the basis of single factor extraction, orthogonal method was used to optimize the experiments. The results showed that the order of affecting the extraction rate of total phenolic acid was extraction temperature, followed by extraction time, ratio of material to liquid, ethanol concentration. The optimum extraction conditions were: extraction temperature 60℃, extraction time 60 min, ratio of material to liquid 1:8, ethanol concentration 70%, and the total phenolic acid of Sedum aizoon L. was 3.62%. The antioxidant capacity of total phenolic acid of Sedum aizoon L. is similar to Vc, which indicates that Sedum aizoon L. has good antioxidant capacity.