Abstract: Three cod skin-derived gelatin with different molecular weights ( Mr > 50 ku, 10 ku < Mr < 50 ku, Mr < 10 ku) were obtained by ultrafiltration technology.They were chelated with calcium to obtain a gelatin-Ca²⁺hemostatic powder material.The hemostatic properties of different molecular weight gelatin-Ca²⁺compound hemostatic powder were studied by fluid absorption ratio and hemostatic experiments in vivo and in vitro, and the hemostatic mechanism was also discussed.The results showed that the liquid absorption capacity of high molecular weight group was the highest, high molecular weight gelatin-Ca²⁺hemostatic powder can significantly ( p < 0.05) shorten the coagulation time in vitro ( 24 s) , reduce rat femoral artery bleeding time ( 114 s) and liver wound bleeding time ( 97 s) . High molecular weight group significantly ( p < 0.01) reduced APTT levels, and affected the endogenous coagulation pathways. High molecular weight gelatin-Ca²⁺hemostatic powder also promoted platelet aggregation, and increase the release of platelet active factors, such as platelet factor 4 ( PF4) , P-selectin, and thromboxane B2 ( TXB2) .Thus, high molecular weight gelatin-Ca²⁺compound hemostatic powder could be considered an effective absorbable hemostatic material in the industrialized production.