The protein of winged bean produced in Huaihua, Hunan was hydrolyzed by complex protease. The effect of the factors on hydrolysis degree was studied by single factor test and orthogonal test. The optimal conditions for complex protease hydrolysising winged bean protein were determined. The result showed that the optimal conditions were temperature 45 ℃, pH value 7.0, enzyme dosage 5%, and enzymolysis time 5 h. In these conditions hydrolysis degree can achieve 18.59%.