Polymer materials have been widely used in various fields of national economy, such as medical treatment, transportation, agriculture, industry, etc. In engineering, most plastic products are processed by extrusion molding, and the single screw extruder is an important processing tool. This article takes the single screw extruder widely used in plastic production as the research object. Based on the Flow Simulation fluid dynamics analysis function in SolidWorks software, the simulation study of its molding process was carried out, and the temperature field, pressure field and velocity field of the fluid inside the extruder were obtained, which could provide theoretical basis and guidance for the design and processing technology of single screw extrusion molding equipment.