Fused deposition modeling (FDM) is an additive manufacturing technology commonly used for three-dimensional printing. The screw rod is an important part of the extrusion nozzle in the FDM manufacturing. The technical parameters of the screw rod, such as the screw pitch, screw angle, groove width, and length-diameter ratio (or aspect ratio), etc., directly determine the speed of extrusion and the precision of modeling. To improve the printing speed and quality of FDM models, this work analyzed the influence of extrusion screw’s parameters on the extrusion flow rate and proposed the best parameters for the screw rod of the FDM process. The results of this work have a crucial significance on the modeling speed and accuracy of the FDM.