An epoxy resin composition is provided. The epoxy resin composition includes 80-100 parts by weight of a thermal curable epoxy resin, and 0.1-20 parts by weight of a branched rubber copolymer. The branched rubber copolymer includes a rubber polymer serving as a main portion, and a polymer composed of polyethylene glycol (PEG), derivatives of polyethylene glycol, polycaprolactone (PCL), derivatives of polycaprolactone, or a combination thereof serving as a branched chain.