Abstract: This study took the whey protein isolation(WPI)without the treatment of ethanol solution as the control group to investigate the effect of different concentrations of ethanol(10%,30%,50%,and 70%,v/v)on the structural properties and emulsifying capacities of whey protein isolate(WPI). The results showed that the ethanol-induced modification could significantly alter the secondary and tertiary structures of WPI. Moreover,lower concentration(less than 50%)of ethanol could induce the unfolding of the protein structure of WPI,while higher concentration(more than 50%)of ethanol could promote the protein aggregation which mainly through disulfide linkage. Additionally,compared with control group,ethanol-induced modification could endow higher surface hydrophobicity and better emulsifying capacities(including emulsifying activity and emulsifying stability)of WPI,and 50% was the optimal ethanol concentration. This results indicated that the ethanol-induced modification was an effective modification method to improve the emulsifying properties of WPI and laid a theoretical foundation for the modification of proteins.