Using vermiculite (VMT) as filler and biodegradable polyterephthalate-butanediol ester (PBAT) as matrix, vermiculite/polyterephthalate-butanediol ester (VMT/PBAT) composite films were prepared by melt-blow molding method. VMT/PBAT/SMA composite films were prepared by adding polystyrene maleic anhydride copolymer (SMA) as compatibilizer. The thermal properties, rheological properties, water vapor barrier properties, micro-structure and mechanical properties of pure PBAT films, VMT/PBAT and VMT/PBAT/SMA composite films were tested. The results show that, compared with pure PBAT films, vermiculite filling reduces the thermal stability of VMT/PBAT composite films, and the addition of SMA compatibilizing agent enhances the thermal stability of VMT/PBAT/SMA composite films. The addition of vermiculite reduces the crystallinity of the composite film by about 2%. The water vapor permeability test shows that the water vapor barrier performance of the two composite films conforms to the national standard. The addition of VMT reduced the tensile strength and elongation at break of VMT/PBAT composite film, while the addition of compatibilizer SMA increased the tensile strength and elongation at break of VMT/PBAT composite film by about 10% compared with that of VMT/PBAT composite film.