Effective control of bleeding is critical to saving lives whether on the battle field or in civilian life. Microporous starch (MS) is a promising hemostat for its extensive sources, huge surface area and good biocompatibility. However, the hemostatic performance of MS is limited because of its complex preparation process and lack of effective component to activate coagulation factors. Herein, porous starch microspheres modified by calcium (Ca-PSM) with dense shell and honeycomb micro-porous core were prepared by electrostatic spray and supercritical CO