The invention discloses a free particle / porous medium composite enhanced boiling structure. The structure comprises a substrate and a porous matrix structure formed on the surface of the substrate, aplurality of pore cavities are formed in the porous matrix structure, and free particles capable of moving in the pore cavity are dispersed in the pore cavity. When the free particle / porous medium composite enhanced boiling structure is prepared, metal particles are sintered to prepare a porous material matrix, the porous material matrix is drilled to form the pore cavity, and then the pore cavityis filled with free particles and sealed. The structure is based on the enhancing characteristics of nucleation activation in the boiling heat transfer process and liquid supply of a liquid absorbingcore to a nucleation site, bubbles are prevented from being mixed and the liquid backflow resistance is reduced by means of bubble nucleation and liquid supply partition. Meanwhile, the free particles collide with one another in the boiling process, so that heat transfer, microlayer evaporation and convective heat transfer in working fluid are enhanced, bubble nucleation is easy, the growth speedis high, the separation frequency is high, and therefore the enhanced boiling heat transfer is realized.