Abstract: In order to reduce allergenic protein content in milk proteins for preparing of infant formula milk, milk protein was hydrolyzed based on screened best enzyme and based on trypsin concentration, hydrolysis time, hydrolysis temperature viewed as influence factors. Single factor experiments and Centure-Composite Design center combination method of three factors and three levels experimental design were used to further opitimaze hydrolysis condition. The results showed that the effect of enzyme concentration and hydrolysis time were significant. The optimum hydrolysis conditions were optimized as following:enzyme concentration 0. 8%, hydrolysis temperature 55℃ and time 47min. Hydrolyted milk was analyzed by SDS-PAGE and determined the antigenicity. The results showed that αs-casein and β-lactoglobulin were degraded in different degrees. The antigenicity of αs-casein and β-lactoglobulin decined .