Abstract: The effects of high hydrostatic pressure processing ( HHP) ( 300 MPa and 600 MPa, 10min) on the protein structure and functionality of whey protein concentrate80 (WPC80) were evaluated. The results showed that a decrease of △E value, and a fluctuation of L*, a* and b* values occurred in color for high pressure treatments. Comparing to the control, the particle size (D50) of 600 MPa treated samples increased by 22.13 times. The HHP treatments did not affect solubility of WPC80 (p>0.05) . However, the foaming and emulsifying ability of WPC80 treated at 300 or 600 MPa for 10 min were changed significantly (p<0.05) . From the bands of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, HHP treatment did not change the molecular weight of the protein significantly. The results of circular dichroism spectroscopy showed that the secondary structure of protein was changed for the HHP treatment.