Aiming at the problems of long plastic melt retention time and burning in the distributor flow channel of plastic extrusion composite machines,simulation optimization was conducted on the distributor flow channel of plastic extrusion composite machines.Methods such as mass continuity equation,momentum control equation,tetrahedral mesh division,Carreau model,simulated working condition VOF model,single-phase flow simulation were used to establish geometric models,mathematical models,material constitutive models,and the internal flow channel mesh division model,the flow process of two types of plastic melts in the distributor were simulated and analyzed under simulated working conditions.The velocity and pressure distribution of the two plastic melts during the flow process in the distributor were mastered,and the pressure distribution,streamline distribution,velocity vector distribution,and flow field analysis at the outlet of the distributor′s original structure were analyzed through single-phase flow simulation analysis,three main areas causing melt retention were obtained.Aiming at the three main areas including the corner of the lateral expansion section,the intersection of three streams of molten metal,and the vicinity of the outlet,an optimization plan for the distributor flow channel structure was proposed,including adding a guide device at the corner of the lateral expansion section,adjusting the tool deviation angle at the intersection of molten metal,and removing the small steps at the outlet.The single-phase flow simulation results of the pressure distribution,streamline distribution,and velocity vector distribution of the structures before and after optimization were compared and analyzed.The optimized structure is significantly better than the original structure,with a more uniform pressure distribution throughout the distributor flow channel,which can greatly reduce melt retention in the three areas and effectively improve the quality of extruded plastic composite film products.