The polypropylene products are injection molded by the dynamic injection molding machine. The performance characteristics of polypropylene products under steady and dynamic injection molding are gained by the DSC indicating methods. Accelerated aging test with hygrothermal test chamber (the aging temperature is 90°C, and the humidity is 95%) is conducted in the study. The regularity for impact strength property of polypropylene is studied during the test in contrast. The change of carbonyl content in the polypropylene products is analyzed both before and after aging by FTIR. The results show that the dynamic injection molding could significantly improve the anti-hygrothermal aging properties of the polypropylene products.