Abstract: The heat-resistant silicone resin was filled with Co₃O₄ nanometer particles to prepare composites to absorb the heat radiation, which was coated on the heat flow transducer. To improve the interfacial properties between Co₃O₄ particles and the matrix resin and to prevent the nano-particles aggregating, the surfaces of Co₃O₄ particles were treated by grafting BMA on them. The grafting characteristics and graft ratio were investigated using infrared (IR) and thermogravimetric analysis (TGA). The effects of the surface treatment of Co₃O₄ particles on the interfacial, endothermal and thermal properties of the composites were analyzed using TEM, the calibrating test of the heat flow transducer, TGA and differential thermogravimetric analysis (DTG). It is found that the surface treatment of Co₃O₄ particles improves their dispersibility in silicone resin, and the response rate of the transducer is also improved greatly. The untreated Co₃O₄ particles deteriorate the thermal properties of the silicone resin. However, after surface treating of Co₃O₄ particles, its thermal properties are improved.