Abstract: The polypropylene (PP) matrix composites reinforced with 20 wt % glass fiber (GF) were prepared by a melt blending method using a twinrotor continuous mixing extruder and an intermeshing corotating twinscrew extruder, and the residual GF length and mechanical properties of composites were investigated to determine the effect of mixing equipment structure with different mixing characteristics. The results indicated that the mechanical properties of PP/GF composites were improved significantly with an increase of residual GF length in the composites. The twinrotor continuous mixing extruder exhibited a better effect on preserving a longer fiber length than intermeshing corotating twinscrew extruder. A proper decrease in rotor speed and dispersibility of twinrotor continuous mixing extruder could preserve a longer residual length of glass fiber in the composites, thus enhancing the mechanical properties more effectively.