The purification process and antioxidant activity of flavonoids from P. kingianum Coll. were studied. Through a single factor test combined with a response surface test, ultrasonic-assisted solvent extraction was used to optimize the extraction process of flavonoids from P. kingianum Coll.. Through static and dynamic experiments, the effects of resin type, crude extract concentration, eluent, and elution flow rate on the adsorption and desorption performance of flavonoids from P. kingianum Coll. were investigated, and the best purification conditions were determined. The antioxidant activity of flavonoids from P. kingianum Coll. before and after purification was compared by DPPH free radical and ABTS free radical methods. The results showed that the optimum extraction parameters were ethanol concentration 79%, extraction temperature of 61 °C, extraction time of 2 h, the ratio of liquid to material 20 mL/g, and the extraction rate reached 0.29%. AB-8 macroporous resin had the best effect on the purification of flavonoids from P. kingianum Coll.. The best condition was that 40 g/L crude extract was put on the column and 70% ethanol was eluted at 2.0 g/L. Under this condition, the purity of flavonoids from P. kingianum Coll. was increased to 5.31%, which was 11.8 times of the concentration of crude extract. The scavenging rates of DPPH and ABTS radicals after purification were 82.44% and 86.22%, which were much higher than those before purification. The study indicates that AB-8 macroporous resin was suitable for separation and purification of flavonoids from P. kingianum Coll. and the flavonoids have antioxidant activity. [ABSTRACT FROM AUTHOR]