In order to understand the flow state of supercritical carbon dioxide （SC-CO₂）-assisted double-base propellant within the metering section during extrusion， and to analyze the distribution and variations of parameters such as pressure， fluid velocity， shear rate， and shear viscosity in the flow field， the CFD simulation software Polyflow was employed for simulating the flow state of the material in the metering section during SC-CO₂-assisted double-base propellant extrusion. The results show that both fluid pressure and shear viscosity decrease with increasing process temperature， gas injection rate， and solvent ratio. An increase in screw speed leads to a decrease in shear viscosity but a sharp increase in fluid pressure. The pressure on the outer wall of the fluid gradually increases in steps， with pressure at the cross-section exhibiting an approximately annular distribution， decreasing gradually from the inner wall of the barrel towards the screw surface. The shear viscosity at the cross-section forms a ring-shaped high-viscosity zone on the center of the screw. The closer the zone is to the inner wall of the barrel and the screw surface， the smaller the shear viscosity. Furthermore， changes in process parameters do not affect the distribution pattern of shear viscosity. The shear rate on the outer wall of the fluid increases with higher screw speed and concentrates at the thread. The maximum fluid velocity at the cross-section occurs near the thread， while the fluid velocity close to the inner wall of the barrel is minimal. As one moves away from the inner wall of the barrel and the screw surface， fluid velocity rapidly increases， with a greater gradient observed in zones closer to the screw surface and the inner wall of the barrel.