The flow form is an important factor that directly affects the quality of polymer plasticization extrusion. Based on the principle of polymer field synergistic plasticization, transportation and mixing, three types of channels were designed, parallel flat channel M1, partially converging channel M2, and fully converging channel M3. The numerical simulation was carried out by using ANSYS Polyflow. Comparative analysis was conducted on the flow patterns of rubber materials under different models and boundary conditions, as well as their effects on mixing performance, tensile/shear ratio, and temperature rise. The results indicate that during the extrusion plasticization process of rubber material, the polymer flow channel has a significant impact on the plasticization quality of rubber material. By comparing the first eigenvalue of the inelastic stress tensor and the mixed evaluation indicators such as time averaged mixing efficiency, it is found that under the same boundary conditions, the mixing performance of converging channels M2 and M3 is better than that of parallel flat channel M1. Among them, M2 has the best mixing performance. When polymer melt flows through the top of the converging channel of M2, it is forced to converge and then diverge, which improves the plasticization quality of the rubber material. In addition, compared with shear flow, the adhesive material generates less viscous heat and consumes less energy in the flow form dominated by tensile flow.