▎ 摘　　要

NOVELTY - Preparation of composite film comprises polishing and cleaning flat glass; mixing 0.01-0.1 wt.% graphene oxide with solvent, stirring to obtain graphene oxide dispersion liquid, adding 25-30 wt.% polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) mixture, stirring to obtain PVDF-HFP/graphene oxide mixed solution, vacuum-degassing at 0.01-0.1 MPa for 3-4 hours, pouring into flat glass, wiping, and heating to obtain composite film; and placing into stretching apparatus, and stretching by 4-5 times at 60-70 degrees C. USE - Method for preparation of composite film used for improving beta -crystal phase content (claimed). ADVANTAGE - The method is simple, solves the low crystallinity and beta -crystal phase content problems of the film, and has low cost.