Objective: To investigate the effect of the screw configuration on the polylactic acid flow field on the structural parameters of the screw on the end face of the screw in the meshing counter rotating twin screw extruder. Methods: The theoretical model of the heterodirectional double-ended threaded element was established by Solidworks software and the geometry of the threaded element after adjusting the structural parameters in two different ways. The established three-dimensional model was imported into Gambit software for meshing, and then Polyflow software was applied to the flow field simulation calculation. Finally, the flow field distribution results were extracted by Fieldview software, and the effects of the adjustment of the structural parameters on the end surface of the threaded element during correction were compared and analyzed on the shear rate field, viscosity field and speed field. Results: The structural parameters of the threaded element during correction will affect the polylactic acid flow field after being adjusted in two ways. The two adjustment methods of structural parameters have reduced the shear rate gradient in the runner to varying degrees, and the first method has also caused the viscosity of the polymer lactic acid in the runner to be reduced. Conclusion: From the perspective of the influence on the shear rate field, viscosity field and speed field, the threaded element adjusted by mode one is more conducive to extrusion, while the solid configuration of the threaded element adjusted by mode two is closer to the theoretical configuration of the threaded component.