Objective: To improve the mixing efficiency and working performance of the new twin-screw extruder. Methods: A new twin-screw extruder with embedded planetary gear train and kneading block was designed. A three-dimensional model was established by SolidWorks, and the flow field analysis of the flow channel was performed by ANSYS/CFS finite element analysis software based on the finite volume method. The Macroscopic pressure diagram, velocity vector diagram, velocity flow diagram were gotten, which was compared with the traditional twin-screw extruder three-dimensional flow field. Results: Under the gradual action of the planetary gear train and the kneading block, the mixing performance and working efficiency of the stepwise acceleration twin screw extruder were significantly better than those of the traditional twin screw. By calculation, the stepwise accelerated twin screw was 20% ~ 25% higher than the traditional twin screw. Conclusion: In the process of continuous acceleration, the gradual acceleration twin screw makes the residence time of the material in the barrel shorter o increase production and reduce energy consumption, and the addition of kneading block makes the material get better shearing.