In recent years, the composite hydrogels composed of micro-nano bioactive glass (MNBG) and gelatin are widely used in tissue regeneration. However, the relationship between hydrogels and MNBG in terms of mineralization and degradation is still unclear. In this paper, gelatin based composite hydrogels with different concentrations of MNBG were prepared, and the effect of MNBG on the mineralization and degradation properties of composite hydrogel was investigated by in vitro experiments. The results show that the composite hydrogel does not affect the bioactive ion release of MNBG, and the formation of negative curvature interface by a high concentration of MNBG aggregates is a necessary condition for composite hydrogels to mineralize. In addition, increasing the concentration of MNBG and quickly mineralizing to form hydroxyapatite layer can effectively reduce the degradation rate of gelatin based composite hydrogel.