Objective：To investigate the effect of dimethyloxallyl glycine（DMOG）-containing gelatin methacryloyl（GelMA）hydrogel on promoting osteogenic differentiation in vitro，and the effect of repairing calvarial bone defects in rats in vivo. Methods：After synthesizing GelMA-DMOG hydrogel，the surface characteristics were observed by scanning electron microscope，and its degradation time was detected in vitro. Mouse osteoblast precursor cells MC3T3-E1 were cultured on the surface of GelMA and GelMA-DMOG hydrogel. The cytoskeleton morphology was observed by fluorescence，and its cytotoxicity was detected by CCK-8 assay. After cultured cells in osteogenesis induction medium，alkaline phosphatase（ALP），alizarin red staining and qRT-PCR were used to detect the effect of two kinds of hydrogel on osteogenic differentiation of MC3T3-E1 cells. A rat calvarial bone defect model was constructed. The effects of GelMA and GelMA-DMOG hydrogels on bone defect repair were observed after 4 and 8 weeks. Results：Compared with GelMA hydrogel，there was no significant difference in the pore size，distribution，and degradation time of GelMA-DMOG hydrogel. The two groups of hydrogel had no significant effect on the proliferation of MC3T3-E1 cells. Compared with control group，the GelMA hydrogel cultured group slightly promoted osteogenic differentiation of MC3T3-E1 cells，while the GelMA-DMOG hydrogel cultured group significantly enhanced the osteogenic differentiation and the expression of osteogenesis-related genes，such as Runx2，ALP，and osteocalcin（OCN）. In vivo，compared with control and GelMA group，the GelMA-DMOG hydrogel group has a much better calvarial bone repair effect. Conclusion：The physical and chemical properties of GelMA-DMOG hydrogel are not changed compared to GelMA hydrogel. In vitro and in vivo experiments show that the GelMA-DMOG hydrogel can promote the repair of bone defects，which opens up a new clinical application of bone tissue engineering in the treatment of bone defects.