To improve the comprehensive properties of soy protein/polyvinyl alcohol films, the effects of reducing agents on the properties of the films were studied. The tensile strength, elongation, transmittance and water absorption of the films were compared. Furthermore, a vague mathematics model was used to evaluate the quality of the films. The experimental results showed that the concentration of TG-B, the reaction of pH, film-forming temperature all have great influences on film properties. When the mass fraction of TG-B was 1.0%, with reaction pH of 6.0, film-forming temperature of 50 ℃, soybean protein / PVA composite films had the best performance. In this condition, tensile strength, elongation, transmittance and water absorption of the film were 8.26 MPa, 53.80%, 16.23% and 67.76% respectively. Compared with the blank without adding TG-B, tensile strength, elongation, transmittance were increased by 75.4%, 162.9%, 27.2%, while water absorption of the film decreased by 25.6%.