The invention relates to a medical incineration fly ash treatment device. The medical incineration fly ash treatment device comprises a high-pressure reaction kettle, an upper filtering chamber and a lower filtering chamber. By arranging all the components, medical incineration fly ash treated through a supercritical water oxidation technology can be efficiently separated from water, the treating water can be converted into circulating water through further reaction and high-efficiency filtering, and accordingly, high harmless treatment of medical waste is achieved.