BACKGROUND: Poly(3-hydroxybutyrate-4-hydroxybutyrate) (P3HB4HB) is a kind of polymer material that can be completely degraded, has good film-forming property and physical properties, but has poor hydrophilicity. OBJECTIVE: To prepare P3HB4HB/polyvinyl alcohol (PVA) coaxial electrospun scaffolds, and to investigate the physical properties and biocompatibility of scaffolds in vitro. METHODS: We prepared P3HB4HB electrospun scaffold, PVA electrospun scaffold and P3HB4HB/PVA coaxial electrospun composite scaffold, and then detected the morphology and characterization, contact angle, and tensile mechanical properties of the scaffolds. Passage 4 bone marrow mesenchymal stem cells (BMSCs) from Sprague-Dawley rats were seeded on the three kinds of scaffolds. Cell adhesion rate was detected at 1, 3, 6 hours after seeding; cell proliferation was detect at 1, 3, 5, 7 days after seeding; and cell viability was observed fluorescence staining at 7 days after seeding. Passage 4 BMSCs were seeded onto the three kinds of scaffolds followed by 14 days of osteogenic and chondrogenic induction. Then, alizarin red staining and toluidine blue staining were used to verify BMSCs differentiation potentials. RESULTS AND CONCLUSION: (1) Scaffold morphology: Under the scanning electron microscope, the structure of the scaffold in each group was a three-dimensional interconnected network. The fiber diameters of P3HB4HB electrospun scaffold and P3HB4HB/PVA electrospun scaffold were homogeneous and ordered. The P3HB4HB/PVA scaffold showed an obvious core-shell structure under the transmission electron microscope. (2) Scaffold characterization: The tensile strength, tensile modulus and maximum stress of the P3HB4HB and P3HB4HB/PVA scaffolds were significantly higher than those of the PVA electrospun scaffold (P < 0.05). The contact angle of the P3HB4HB/PVA composite scaffold was less than 90°. (3) Cell adhesion rate was ranked as follows: PVA electrospun scaffold group >P3HB4HB/PVA composite scaffold group > P3HB4HB electrospun scaffold group (P < 0.05). (4) Proliferation and activity of cells: The cell proliferation of the P3HB4HB/PVA composite scaffold group was faster than that of the other two groups at 5 and 7 days (P < 0.05). There were more viable cells on the PVA electrospun scaffold and composite scaffold than on the P3HB4HB electrospun scaffold. (5) Cell differentiation: Osteogenesis and cartilage specific staining of the composite scaffold were stronger than those in the other two groups. Overall, the P3HB4HB/PVA coaxial electrospun scaffold has good biocompatibility and a certain mechanical strength.