Disclosed are a polypeptide polymer-doped bone marrow cavity filler and the use thereof in the treatment of osteomyelitis, wherein the polypeptide polymer is used for being doped in a bone marrow cavity filler or preparing a bone marrow cavity filling antibacterial material for treating osteomyelitis, has efficient antibacterial activity on common staphylococcus aureus, etc., in osteomyelitis, is not easy to induce bacteria to generate drug resistance, has good biocompatibility in environments such as bone marrow and blood, has good stability, and still keeps activity after forming heat release and even the autoclaving of bone cement.