Ultrasonic-microwave synergistic method was used to extract the total flavonoids from Microcos Paniculata L. To optimize the extraction process, we have conducted single-factor experiments on the total flavonoids yield to provide a basis for analysis. After the results were evaluated, we carried out the response surface method to test the antioxidant properties of total flavonoids in Microcos Paniculata L. The evaluation of antioxidant capacity was done from four dimensions. According to the experiments, the optimal extraction parameters included: 40 mesh particle size, 20:1 liquid/feed ratio (mL/g), 250 W ultrasonic power, 400 W microwave power, 30 min extraction time, and a 60% volume fraction of ethanol. When all the conditions were met, the yield of total flavonoids from Microcos Paniculata L. could reach 6.01%. The total flavonoids from Microcos Paniculata L. could remove DPPH.and ABTS+. At the same mass concentration, the scavenging rates. were as high as 93.14% and 84.40%, respectively. They were close to the scavenging rates of Vc in the positive control group. This proves that the total flavonoids in Microcos Paniculata L. have a good antioxidant ability.