This study investigates the effect of nano-silica particles on the mechanical properties of hybrid Polypropylene/Glass Fiber composites produced from reinforced weft knitted fabrics. Full-Cardigan structure which contains knit- and tuck-stitches, was produced on a flat knitting machine using Polypropylene (PP) yarns. To reinforce the weft knitted fabrics, Glass Fibers (GF) were employed as the weft yarns in the fabric structures. Produced fabric samples were then hot-pressed using the hot pressing machine in order to prepare the PP/GF composites. In order to produce PP/GF weft-knitted composite samples with nano silica-filler, the PP granules and SiO nanoparticles were mixed together using twin-screw extruder and then used as matrix filler. Three different percentages of nano-silica particles (1.5%, 3% and 4.5 wt. %) were added to matrix. The results revealed that nanosilica particles improved effectively the impact and tensile strength of the hybrid composite.