The invention discloses a method for realizing efficient heat-work conversion. The method comprises the following steps of 1, inflating a liquid state oxidizing agent to more than 2 MPa; 2, to performing constant voltage vaporization on the inflated liquid state oxidizing agent; 3, guiding the vaporized liquid state oxidizing agent into an internal combustion combustor, and enabling the liquid state oxidizing agent in the internal combustion combustor and a fuel to generate a combustion chemistry reaction so as to form a high-temperature gas working medium; and 4, guiding the high-temperature gas working medium into a speed-type acting mechanism, wherein the speed-type acting mechanism is used for outward outputting power. The method for realizing the efficient heat-work conversion which is disclosed by the invention, has the advantages that the problems that the efficiency of an existing internal combustion engine and an existing external combustion engine is low, the pollutant discharge is serious and the diversity of a fuel is poor can be well solved, the structure is simple, the power density is high, the efficiency is high, and the cost is low.