Thermally conductive composite film was obtained from silicon carbide (SiC) and linear low-density polyethylene (LLDPE) by powder mixing and hot press molding. SiC powder distributions were found to be relatively rather uniform at both low (20 wt.%) and high (60 wt.%) filler content. The effect of the content and the particle diameter of filler on the properties of SiC/LLDPE composites was investigated by thermal conductivity measurement, TGA, tensile test and dielectric properties measurement. The results demonstrated that the thermal conductivity and dielectric constant of LLDPE film increased from 0.32 Wm À1 K À1 and 2.10 to 0.98 Wm À1 K À1 and 4.18 with 50 wt.% SiC loading. The TGA data showed SiC filler slightly increased the thermal stability of LLDPE. While the tensile properties of LLDPE obviously decreased with the increase of SiC. Compared with the untreated SiC filler, KH-550 slightly improved the thermal conductivity of SiC/LLDPE composites. For thermal conductivity, smaller particle is superior to larger particle. Compared to that with single-scale particle, the composites filled with hybrid SiC particle exhibited higher thermal conductivity.