According to the requirements of aluminum conductor composite cores, a kind of resin system was developed with TGDDM as main body, and self-made flexible epoxy SUC-1 as auxiliary, plus methyl hexahydrophthalic anhydride as curing agent. The gel rate of the system was high enough to meet the demands of pultrusion technique. The heat deformation temperature of cured sample reached 194°C, and the tensile strength achieved 62.95Mpa. The elongation at break matched that of carbon fibers. The interfacial bonding between the matrix and the fibers, observed by scanning electron microscope, was tight without debonding phenomenon.