In this study, the formulation and optimization of the properties of thermoplastic polyamide elastomers (TPAEs) were evaluated by a mixture response surface methodology. The TPAEs prepared from different chain extender blends of adipic acid, terephthalic acid (TPA), and C36 dimer acid were characterized by specific gravity measurement, water absorption measurement, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicate that the specific gravity of the polymers increased and the water absorption of the polymers decreased as the content of TPA increased. The DSC data show two major endotherms corresponding to the melt of poly(tetramethylene ether) glycol (PTMEG) and nylon-6 segments. The TGA data show that the thermal degradation temperatures of the polymers increased as the C36 dimer acid content increased.