A composite mold includes a mold base, a protective film provided on the mold base, and a water-cooling heat dissipation system disposed within the mold base. Wherein, the protective film is comprised of with a plurality of RexIry layers and a plurality of SiC layers, the RexIry layers and the SiC layers are alternatively stacked one on another, x is in the range from 0.25 to 0.55, and y is in the range from 0.45 to 0.75. Alternatively, the protective film is comprised of an RexIry layer, a catalyst layer and a carbon nanotube layer in that order, x is in the range from 0.25 to 0.55, and y is in the range from 0.45 to 0.75.