In order to investigate the effects of the novel dynamic three-screw extrusion moulding technology on the mechanical properties of the specimen, PP/CaCO3 composites were selected as the object to reveal the vibration parameters on the mechanical property and the section morphology structure. In the investigation, the vibration force with a frequency varying from 0 to 60 Hz and an amplitude varying from 0 to 250 μm was loaded on a three-screw extruder, and the tensile strength and the impact strength of the specimens were tested, followed by a SEM measure ment. The results show that there exists an optimum point for the response of mechanical properties to vibration parameters, and that, as compared with the extrusion in the steady state, the composites show an increase in impact strength by 21.7% at a 20 Hz and 225 μm vibration, and an increase in tensile strength by 10.4% at a 20 Hz and 145 μm vibration.