Abstract: In this study, a series of blends with different starch content (30%-60%) and amylose/amylopectin ratio (65/35-20/80) were designed to investigate the effect of starch composition on the structure and properties of the films in starch/polybutylene adipate-glycol terephthalate (PBAT)/polylactic acid (PLA) blends. A series of starch/PBAT/PLA blend films were prepared by twin-screw extrusion (zone Ⅰ:60℃, zone Ⅱ:120℃, zone Ⅲ:170℃) combined with hot pressing (50 kN, 170℃). The variation trends of microstructure (surface morphology and fracture section structure), mechanics (tensile strength, elongation at break and Young's modulus), barrier properties (water and light transmittance) and surface hydrophobicity of films were investigated. The interaction mechanism between starch and bio-polyester was discussed. The results showed that the film with 50% starch content and 65% amylose content had the highest mechanical properties (tensile strength 18.22 MPa, modulus 449.8 MPa), and the film surface was uniform and smooth. The fracture surface of the film showed a double-continuous winding structure of starch and bio-polyester. With the increase of starch content and amylose ratio, the water vapor permeability was improved, as well as the ultraviolet light shielding effect of all films (less than 1%). Water contact angle measurements showed a change from high hydrophobicity (102°/68.6°) to weak hydrophilicity (64.5°/54.7°). The results could be used to guide the selection of raw materials for starch-based blends.The tensile strength and modulus of the films were improved with high amylose content of starch. The higher the proportion of branched chain in starch, the better the moisture barrier property of the film. Finally, in order to study the degradation efficacy of the film, soil in natural environment was collected. It was found that starch component could promote degradation. Therefore, such films are environmentally friendly and this study provides a theoretical basis for the preparation of degradable materials.