The utility model relates to the technical field of heat insulation. The utility model discloses a heat insulation structure, in particular to an inner-layer nano-microporous heat insulation structurefor a smelting furnace. Mounting frame, one side of the mounting frame is provided with an opening; the mounting frame is of a rectangular structure; a nano material is fixed at the bottom of an inner cavity of the mounting frame; an infrared radiation reflecting material is fixed on the side surface, facing the opening direction of the mounting frame, of the nano material; a blocking thermal insulation material is fixed to the side face, away from the nanometer material, of the infrared radiation reflection material, cylindrical plugs are rotationally installed at the four corners of the side face, away from the opening, of the installation frame, and two symmetrical clamping blocks are fixed to the ends, away from the installation frame, of the cylindrical plugs. In the utility model, the nano material is low in heat capacity, low in heat conductivity, good in elasticity, long in service life, excellent in chemical stability, excellent in heat stability and shock resistance, not easy to pulverize at high temperature and easy to form and cut, and the device can reduce heat conduction, reduce heat convection and block heat radiation.