The foam fractionation of quinoa protein was optimized by response surface methodology, based on the single-factor test, Box-Behnken design was adopted to investigate the influence of four factors: the ratio of material to solvent, the loading liquid volume, temperature, and pH value on recovery and enrichment ratio of quinoa protein, and the subunit distribution and functional properties of quinoa protein were studied. The optimum conditions for the foam fractionation of quinoa protein were found to the temperature of 35.30℃, pH value of 3.98, the loading volume of 259.61 mL, the ratio of material to solvent of 0.29 mg·mL-1, under the conditions, the recovery of quinoa protein was 96.71% and the enrichment ratio was 7.27. The actual process was considered, the optimization process was the temperature of 35℃, pH value of 4.0, the loading volume of 260 mL, the ratio of material to solvent of 0.3mg·mL-1, under the conditions, the recovery of quinoa protein was 95.68% and the enrichment ratio was 7.89. The SDS-PAGE analysis showed that quinoa protein had basic subunits with molecular weights of 50, 32~39, 22~23, and 8~9 kDa. The functional properties and antioxidant activity of quinoa protein were studied, and the results showed that the highest water-holding capacity of quinoa protein was 9.733 g/g at 60℃, and the highest oil-holding capacity was 5.848 g/g at 60℃. With the increase of the ratio of material to solvent, the emulsifying capacity (EC), emulsion stability (ES), the foaming capacity(FC), and foam stability (FS)of quinoa protein tended to increase and then decreased.The scavenging rate of DPPH radical was positively correlated with the dose. When the concentration of quinoa protein was 2.5mg/mL, the scavenging rate of DPPH radical reached (56.01±1.34)%.