The present invention relates to a thermoplastic resin composition. In more particular, a thermoplastic resin of graft ABS polymer and heat-resistant copolymer contains acryl-based resin, peroxide-based additive, or cross-linking additive, so that the thermoplastic resin composition of the present invention is effective in processing of a colored heat resistant ABS resin by having excellent cold stress whitening reduction and strength property, without lowering other properties as well as giving excellence in hot-tool weldability, pigmentation and paint spread property which are more important in post process, and maintaining the mechanical property as well as giving excellent heat-resistance and low gloss property.