〔Abstract〕 Objective To prepare the gelatin methacryloyl(GelMA)/hydroxyapatite(HA) composite hydrogel scaffold by additive manufacturing(AM) technology, and to explore its feasibility as a scaffold for repairing in bone tissue engineering via characterizing microstructure and testing biocompatibility. Methods The GelMA solution and hydroxyapatite particles were uniformly mixed to prepare a bio-ink firstly.Then, AM technology was used to fabricate the GelMA/HA composite hydrogel scaffold.The microstructure and components of the composite scaffold were characterized and analyzed by scanning electron microscope(SEM) and transmission electron microscope(TEM).The Young′s modulus of pure GelMA scaffold and the composite scaffold was measured by a mechanical tester.Cell counting kit-8(CCK-8) and Live/dead cell staining were used to evaluate the cytocompatibility of scaffolds.Alkaline phosphatase(ALP) staining was used to explore the osteogenic properties of scaffolds. Results The GelMA/HA hydrogel scaffold showed a porous and lattice-like structure and exhibited stiffer than pure GelMA scaffold.The live-dead cell staining experiment exhibited that BMSCs grew well and displayed a spread morphology on the composite scaffold after 7 days of culture.Cell proliferation experiments showed that the proliferation rates of BMSCs in pure GelMA hydrogel scaffold group and the GelMA/HA composite hydrogel scaffold group cultured for 3 and 7 d were higher than those of the blank group(P<0.05).The ALP staining experiment revealed that the positive ALP stained area of the GelMA/HA composite hydrogel scaffold significantly increased(P<0.05) compared with the blank group and pure GelMA hydrogel scaffold group. Conclusion The GelMA/HA composite hydrogel scaffold processes good biocompatibility and promotes the osteogenic differentiation of BMSCs, which has a potential to be used as a filling and repair scaffold for bone tissue engineering.