Abstract: The mixture of β- lactoglobulin( β- LG) and oleic acid was treated by dynamic high pressure mircrofluidization( DHPM). The effect of interaction with oleic acid on the functional properties and surface hydrophobicity of β- LG during DHPM treatment was investigated. Compared with standard β- LG,the functional properties and surface hydrophobicity of the unteated mixture had no significant changes( p > 0.05). With DHPM pressure increasing from 40 MPa to 160 MPa,the functional properties and surface hydrophobicity of β- LG / oleic acid complex were increased initially and then decreased.At 80 MPa,the solubility and foaming activity of complex were the biggest,respectively,95.36% and 32.00%,while the maximum surface hydrophobicity and emulsifying activity of 640.20,1.09 were obtained at 120 MPa respectively.A positive correlation between surface hydrophobicity and emulsifying activity was observed.The results indicated that the changes of functional properties and surface hydrophobicity were related to the extent of the interaction between β- LG and oleic acid altered by DHPM treatment.