The invention discloses a heat exchange method of mainstream gas of an aero-engine. The heat exchange method comprises the Brighton circulation in a mainstream flow path, and further comprises the supercritical state fluid circulation, wherein the two circulations are independent from each other; in a compressor, cooling channels are formed in blades of each stage of the compressor, and are filled with porous microscale mediums; and supercritical cooling fluid flows through the cooling channels filled with the porous microscale mediums so as to realize the heat exchange between mainstream air of the compressor and the supercritical mediums. The supercritical state is that the pressure and temperature of the fluid are far higher than the critical pressure and temperature; and the microscale is that the geometric scale is millimeter or submillimeter. Compared with the prior art of performing the interstage heat exchange by adopting a heat exchanger, the heat exchange method can effectively reduce the weight of the aero-engine and the load of the compressor, and can further improve the heat exchange efficiency.