Abstract: Glycerol, polyethylene glycol and sorbitol, which were commonly used as plasticizers, were selected to study the effects of plasticizers on the permeability of soy protein isolate (SPI) films. The effects of the three plasticizers and their additions on the selective permeability of O₂, CO₂, and permeability ratios of SPI films were studied. The results showed that the ratio (β) of CO₂ permeability (P(CO₂)) to O₂ permeability (P(O₂)) of SPI film with plasticizer glycerol, polyethyleneglycol or sorbitol was concentrated within 1-2, and the P(O₂) and P(CO₂) increased with the increase of plasticizers mass fraction. Because the change rules of O₂ transmittance and CO₂ transmittance were approximately the same, β changed little with the mass fraction of plasticizer. The film selectivity of polyethylene glycol as plasticizer was better than that of glycerol and sorbitol, and the change of glycerol mass fraction presented the greatest effect on β. Therefore, the suitable plasticizer can be selected according to the packaging object of SPI film, so as to achieve the ideal permeability. The results can provide reference for the preparations of intelligent edible films, particularly SPI films.