This thesis is aimed to the external instantaneous high energy heat source, according to enclosed metal cavity, porous medium in the cavity, porous media can by phase change heat transfer characteristic of variegated medium coupling state target’s special requirements in the field of aerospace, it is innovatively to put forward a kind of applicable to simulate sealed coupling target, under the condition of instant high energy heat source excitation, By heat source-metal cavity-porous medium—porous medium’s phase-changeable phase change process heat-transfer characteristic numerical calculation model-creation approach, in use of the metal cavity, in the porous medium incompressible flow phase transition of working medium’s heat energy conservation, momentum conservation and mass conservation principle, it is to establish analysis model of coupled heat transfer characteristics of multiple parts, in order to acquire the full target area of airtight coupling state targets, temperature field, pressure field, velocity field and phase change of phase transition of working medium characteristics change with time and space change numerical value to analog result. The study results points out: when the incentive heat source keep constant, the change rule of full target area temperature, pressure flow rate and phase change characteristic parameters is in conformity with theory of heat transfer medium. The heat transfer model can be popularized and applied to the optimization design of incentive heat source, and comprehensive performance optimization of enclosed coupling state objects.