A pure oxygen direct combustion system using a liquid metal according to the present invention comprises: a reactor for receiving a liquid metal; a heat exchanger, connected to the bottom of the reactor, for exchanging heat for the liquid metal; a circulation pump, connected to the heat exchanger, for circulating the incoming liquid metal; a nozzle, connected to the circulation pump and disposed on the reactor; a reduction unit, connected to the circulation pump, for performing a reduction for the oxidized liquid metal; and a separation unit, connected to the reactor and the reduction unit, wherein the particles of the liquid metal injected from the nozzle are subjected to sensible heat from the gas generated from the reactor, heat-exchanged by the heat exchanger and regenerated by the reduction unit, and then supplied back to the reactor.