AbstractThe block copolymers PEF/PBAT were synthesized by copolymerizing ethylene 2,5‐furandicarboxylate (EF) with totally biodegradable poly (butylene adipate‐co‐terephthalate) (PBAT). The copolymers' molecular chain structure, thermal properties, thermal stability, and mechanical properties were investigated, and the toughening mechanism was preliminarily studied via the micromorphology. The results revealed that the prepared block copolymers were amorphous, the thermal stability of PEF was improved, while the glass transition temperature decreased with the increase of PBAT content. PBAT was enhancing the tensile strength and elongation at break of PEF simultaneously. When the PBAT content was 25% (PEF/PBAT‐25), the brittle‐ductile transition occurred, with the tensile strength, Young's modulus and elongation at break of 72 MPa, 3210 MPa and 287%, respectively. The copolymers have broad application in the field of packaging materials.