Abstract: To study the effects of ultra-high pressure microfluidization on physicochemical properties and the structure of peanut protein, the change laws of particle size, free sulfhydryl, surface hydrophobic groups and ultraviolet absorption groups of peanut protein after ultra-high pressure microfluidization treatment were analyzed. The results indicated that the particle size and free sulfhydryl of peanut protein decreased after ultra-high pressure microfluidization treatment, but the surface hydrophobic groups and ultraviolet absorption groups of peanut protein increased. Ultra-high pressure microfluidization treatment can destroy the inner groups of peanut protein, then lead to the change of protein structure.