Uncontrollable bleeding and bacterial infections are the major reasons for the high mortality of post-traumatic. In this study, a composite hemostatic chitosan sponge CaO₂@SiO₂/CS was prepared by combining a novel core–shell inorganic nano hemostatic CaO₂@SiO₂ nanoparticles with carboxylated chitosan, which presents a multi-layered structure with a rough and hydrophilic surface for rapid absorption of blood. When the CaO₂@SiO₂ nanoparticles in the CaO₂@SiO₂/CS come into contact with blood, the silanol group on its surface and the released H₂O₂ and Ca²⁺ can recruit and activate platelets, while generating fibrin clots and activating the endo-exogenous coagulation cascade reaction to achieve rapid clotting. The H₂O₂ released from CaO₂@SiO₂ shows the antimicrobial capacity and stimulates the production of tissue factors by endothelial cells. Meanwhile, the silica coating reduces the cytotoxicity of bare CaO₂, thus reducing the risk of secondary bleeding at the site of vascular injury. CaO₂@SiO₂/CS (48 s) showed a 1.83- and 2.52-fold reduction in hemostasis time compared to commercial gelfoam and CS in a femoral artery hemorrhage model. This study illustrates the hemostatic mechanism of CaO₂@SiO₂ and provides a reference for the development of clinical biomedical inorganic hemostatic materials.