Equipping a gear pump in front of the extruder, checking pressure before the pump and controlling the speed of extrusion, which can minimizing pulsation and irregular material feeding and ensures the polymer is smoothly extruded and continuously delivered to the die head. The system can be widely used to measuring and adding pressure for PC, PMMA, ABS, PET, PVB, PS, PP, PE. The shell of the pump adopts high-quality alloy-steel and the gear uses quenched chrome steel or other high-grade metallic materials which ensures high efficiency and leakage-proof.