In order to improve the functional properties of oat protein and extend its application in food industry, oat bran protein isolates(OBPI) were prepared from oat bran and hydrolyzed by using trypsin. Protein hydrolysates of three different degrees of hydrolysis(DH)(4.1%, 6.4% and 8.3% respectively) were obtained. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) analysis results show that oat globulin is the major protein component in OBPI. After trypsin treatment, acidic polypeptides of globulin were partly degraded; however, basic polypeptides were almost intact. The functional properties of products were compared with those of control OBPI. Marked changes in the protein functionality were caused by proteolysis. The solubility, water-holding capacity, emulsifying activity and foaming ability of hydrolysates increased gradually with the increase of DH. However, the oil-holding capacity, emulsifying stability and foaming stability of the hydrolysates reduced to a certain extent.