To improve the bio-applicability of alginate hydrogel, the composite hydrogels of oxidized sodium alginate (OSA)/cellulose nanocarrier (CNCs)/ polyacrylamide-gelatin (PAM-GT) were constructed from combination of interpenetrating network technology, CNCs reinforcement and GT surface deposition with OSA. The effects of CNCs dosage on the structure and properties of OSA/CNCs/PAM-GT composite hydrogels were analyzed by FTIR, TGA, XRD, SEM, swelling and degradability experiments as well as cytocompatibility tests. The results showed that CNCs could interact with the polymers in the matrix. As the dosage of CNCs increased, the composite hydrogel exhibited a decreased porosity, enhanced mechanical strength and biodegradability, and a slightly reduced swelling, indicating that CNCs could regulate the physicochemical properties of the composite hydrogels to a certain extent. Meanwhile, the composite hydrogels displayed good cell adhesion, proliferation and differentiation properties. When the dosage of CNCs was 0.5%(based on the mass of OSA solution, the same below), the composite hydrogel showed the best cell proliferation activity for MG63 cells, while displayed the most significant cell differentiation activity when the dosage of CNCs was 1.5%.