Abstract: To modify the comprehensive properties of soy protein/polyvinyl alcohol (PVA) films, 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 quality of the films.Experimental results showed that the addition of nano-SiO2, addition of dispersant and pH of film liquid all had effects on the properties of the soy protein/PVA films.And the optimum film-forming conditions were 1.0% SiO2 nanoparticles (based on the dry weight of soy protein and PVA) , 1.5% PVP (based on weight of SiO2 nanoparticles) and pH4.0, then tensile strength, elongation, transmittance and water absorption of the films were 9.71MPa, 89.86%, 25.07%, 48.35%, respectively.