The effect of CO₂ on thermoplastic polyurethane (TPU) hydrogen bond structure was studied by FT-IR at high pressure. The effect of CO₂ annealing at low temperature on the TPU crystallization and tensile strength was studied by XRD and SEM. The results show that a Lewis acid-base interaction occurs between CO₂ and polar groups of TPU, and the hydrogen bond degree of TPU is decreased by this interaction. The crystallization degree of TPU is increased due to CO₂ induced crystallization. The tensile strength of TPU is enhanced with increasing crystallization. The tensile strength of TPU with slight foaming after CO₂ annealing is higher than that without foaming.