Abstract: The purpose of this study was to find out the optimal process parameters of the extraction of black bean protein isolates assisted by ultrasonic, using response surface analysis method. The results indicated that the optimal extraction conditions were: the ultrasonic time was 24 min, p H9.7, ultrasonic power was 378.5W, liquid-material ratio was 11 ∶ 1. Under the optimal process parameters, the extraction yield of black bean protein could reach 56.26%.Meanwile, results showed that the functional properties of black bean protein extracted by ultrasonic were better than those of protein extracted by traditional alkali soluble acid extraction, eg. solubility, emulsification and emulsion stability, foaming ability and foam stability.