The study developed a composite hydrogel containing magnesium-doped nano-hydroxyapatite (Mg-nHA), polyvinyl alcohol (PVA), and chitosan (CS) using magnetic stirring-ion exchange and repeated freeze-thaw-physical cross-linking techniques. The hydrogel exhibited a well-defined 3D spatial structure with micropores, and its chemical structure, porosity, and elemental composition were analyzed using various techniques such as SEM, FTIR, EDS, and XPS. The hydrogel demonstrated favorable water content, enhanced biocompatibility, and porosity similar to human cancellous bone. It maintained an equilibrium swelling degree and released magnesium ions, creating an alkaline environment that promoted osteogenic differentiation. In vitro experiments showed that the hydrogel facilitated the proliferation of bone marrow mesenchymal stem cells (BMSCs) and their osteogenic differentiation. The optimal concentration of Mg-nHA was found to be 5%, as it exhibited the highest mineralization properties and cell viability. The Mg-nHA/PVA/CS hydrogel shows significant potential for bone repair and tissue engineering applications. However, limitations include the need for further research on real-world application environments and the impact of uneven heating during testing.The study developed a composite hydrogel containing magnesium-doped nano-hydroxyapatite (Mg-nHA), polyvinyl alcohol (PVA), and chitosan (CS) using magnetic stirring-ion exchange and repeated freeze-thaw-physical cross-linking techniques. The hydrogel exhibited a well-defined 3D spatial structure with micropores, and its chemical structure, porosity, and elemental composition were analyzed using various techniques such as SEM, FTIR, EDS, and XPS. The hydrogel demonstrated favorable water content, enhanced biocompatibility, and porosity similar to human cancellous bone. It maintained an equilibrium swelling degree and released magnesium ions, creating an alkaline environment that promoted osteogenic differentiation. In vitro experiments showed that the hydrogel facilitated the proliferation of bone marrow mesenchymal stem cells (BMSCs) and their osteogenic differentiation. The optimal concentration of Mg-nHA was found to be 5%, as it exhibited the highest mineralization properties and cell viability. The Mg-nHA/PVA/CS hydrogel shows significant potential for bone repair and tissue engineering applications. However, limitations include the need for further research on real-world application environments and the impact of uneven heating during testing.