Abstract: Explored the whey protein functional properties change under alkaline protease restrictive hydrolysis. Using whey protein solubility,emulsification and emulsion stability,foaming and foaming stability as indicators and determined the whey protein isoelectric point and analyzed different degree of hydrolysis of whey protein different functional properties under the p H.The results showed that whey protein isoelectric point was 4.8. Whey protein functional properties had greatly improved under limited enzymatic hydrolysis.Hydrolysis reached the maximum under DH14,p H10,higher than native protein 14.55%,foaming reached the maximum higher than native protein 107.5% under DH14,p H4,foaming stability reached the maximum under DH4,p H4 higher than native protein 8.66%; emulsifying reached the maximum under DH14,p H12 higher than native protein 56.1%,emulsion stability reached the maximum under DH4,p H12 higher than native protein 50.42%.