Objective: In order to explore the distribution law of the flow channel of polylactic acid in different screw contact states of the counter-rotating twin-screw extruder. Methods: Partially meshing screw and non-meshing screw were established by Solidworks software. Numerical sim-ulation was carried out using POLYFLOW fluid simulation software. The pressure field, shear rate field and viscosity field of polylactic acid fluid under different contact states of three screws were compared. Results: The counter-rotating twin-screw extruder in the partially meshed state has better pressure-building ability and dispersing and mixing ability for polylactic acid. Conclusion: The extrusion effect of polylactic acid in the partially meshed state is better than the other two screw contact states.