Disclosed are a thermoplastic polyamide resin composition, a method for preparing the same and a molded article produced thereby. The molded article may have improved impact strength and heat resistance, produced from the thermoplastic polyamide resin composition including a nucleating agent containing an aromatic polyamide and a heat-dissipation filler, polyamide 66 and polyamide 6, thereby improving the speed of process and realize uniform crystallization.