This study investigated the effect of co-incorporation of two different kinds of nanomaterials with different forms, layers Na-montmorillonite (Na-MMT) and particles (MCM-41), into the polymer matrix on morphology and mechanical properties of polypropylene (PP) composites. PP/Na-MMT/MCM-41 nanocomposites were prepared by melt blending. The X-ray diffraction (XRD) measurement showed that the Na-MMT layers were exfoliated and the hexagonal framework structure of MCM-41 was retained during and after the composite preparation. Scanning electron microscopy (SEM) observations revealed that the nanomaterials were well dispersed in the polymer matrix and the enhancement of the interface between the matrix and fillers were obtained. The results of mechanical tests showed that at same nanomaterial loading, the co-incorporation of Na-MMT and MCM-41 into the PP matrix gave rise to much better enhanced effects than incorporating either Na-MMT or MCM-41 particles separately due to different interfacial structure between the fillers and the matrix.