A resin composition is provided, which includes 1 part by weight of (a) thermally conductive resin with a biphenyl group, 1.0 to 10.0 parts by weight of (b) polyphenylene oxide, 0.01 to 5.0 parts by weight of (c) hardener, and 0.1 to 5.0 parts by weight of (d) inorganic filler. (d) Inorganic filler is boron nitride, aluminum nitride, silicon nitride, silicon carbide, aluminum oxide, carbon nitride, octahedral carbon, or a combination thereof with a surface modified by iron-containing oxide. (d) Inorganic filler is sheet-shaped or needle-shaped.