Abstract: Thermally conductive composite reinforced by glass fiber was prepared by heatpress molding, using polyimide modified epoxy resin as a matrix, alumina modified by KH550 as thermal conductive filler. The thermal, mechanical, and dielectric properties were studied. It showed that thermal conductivity of the composites increased with increasing content of Al2O3. When the content of Al2O3 reached 50 %, the thermal conductivity was up to 1.239 W/（m·K）. The impact and bend strengths increased first then decreased. When the content of Al2O3 was 20 %，the ultimate values were 376.3 kJ/m2 and 912.6 MPa, respectively. The composites modified using polyimide possessed good dielectric properties, thermal stability, and thermal aging resistant.

Key words: epoxy resin, polyimide, alumina, glass fiber reinforcement, thermal conductivity