Ultrasound-assisted propyl alcohol ammonium sulfate aqueous two-phase extraction of polyphenols from Phyllanthus urinaria L.was investigated.The best condition for the single factor experiment was: propyl-alcohol concentration 60.0%,liquid/solid ratio B 25.0,extraction time C 30min.A Response surface methodology,with a five levels,four variables central composite designs was applied based on the single factor optimization experiment.The best condition was: propyl-alcohol concentration 53.65%,liquid/solid ratio 23.97,extraction time 28.19 min,and ammonium sulfate concentration 0.40 g/ml.An experimental extraction yield of 8.72 %(n=5)was achieved under the optimal extraction which was very close to the optimal prediction extraction yield(8.67 %),and was higher than that of single factor optimization experiment(8.61 %,n=5).