Polypropylene/polycarbonate (PP/PC) nanocomposites containing various proportions of the organically modified montmorillonite were prepared by extrusion and injection molding process. The morphology of PP/PC nanocomposites was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The nanocomposites with 3 or 5 wt% of nanoclay (NC) show a uniform dispersion of the NC as pointed out by two different methods, TEM and XRD. It was shown that the morphology of dispersed phase (PC) is highly dependent on the content of minor phase, which was correlated with the balance of drop breakup and coalescence. The mechanical properties have been investigated by tensile test and Izod impact test. The virgin PP/PC samples showed a reduction in impact strength and elongation at break and up to 50% increase in Young's modulus by increase in PP content comparing with the pure PP. Investigating the effect of NC and PC content on the mechanical behavior of PP/PC nanocomposites showed increased Young's modulus and decreased impact strength with increasing PC and NC loading. An obvious ductile to brittle behavior transition at a high content of PC or NC was supported by notched Izod impact strength experiments and SEM results.