The wall thickness distribution and its uniformity characteristics of liquid carbon dioxide-assisted injection molding (LCO2-AIM) pipes and influence of process parameters were investigated based on experimental means. Comparison with gas injection assisted molding (GAIM) and water injection assisted molding (WAIM) pipes shows that the wall thickness of LCO2-AIM pipes decreases and then increases along the flow direction, while the wall thickness of GAIM and WAIM pipes increases gradually along the flow direction, and that the wall thickness of LCO2-AIM molded pipes is thinner and more homogeneous than that of GAIM and WAIM molded pipes. Through the one-way experimental method, it is found that among the five process parameters: melt temperature, injection delay time, LCO2 injection pressure, melt injection pressure and mold temperature, the injection delay time has a significant effect on the wall thickness of the LCO2-AIM pipes, and the wall thickness of the pipes increases with the increase of the injection delay time, while the melt temperature, LCO2 injection pressure, and mold temperature have a smaller effect on the wall thickness of LCO2-AIM pipes; the process parameters have a small effect on the wall thickness uniformity of pipes.