Abstract: Using the sol-gel method， the nano-SiO₂ modified PVA/soluble starch composite film was prepared by adding a nano-silica （SiO₂） suspension to the soluble starch and polyvinyl alcohol（PVA）blend system，and using polyacrylamide（PA），glycerin and glutaraldehyde as dispersants and plasticizers. The tensile strength，elongation at break，light transmittance，and haze of the composite film were tested，and the results of SEM，FT-IR，DSC and XRD were comprehensively evaluated. The experimental results show that the composite film has the best comprehensive performance when the content of SiO₂ is 3% and the mass of glycerol and glutaraldehyde is 1. 0%. The results of FT-IR，XRD，DSC，and SEM show that nano-SiO₂ is added to produce hydrogen bonds or Si—O—C with soluble starch and PVA molecules. The composite film plays a cross-linking role to form a spatial network structure，effectively improving the comprehensive performance and heat resistance of the composite film.

Key words: soluble starch, nano-SiO₂, plasticizer, composite film