We have prepared the intercalated nanocomposites of polypropylene (PP)/clay (PPCNs) successfully using maleic anhydride modified PP (PP-MA) and organophilic clay via melt extrusion process. The hierarchical structure of the PPCNs from the structure of confined PP-MA chains, in the space a few nanometer width between silicate galleries to crystalline lamellae of 7-15 nm thickness and spherulitic texture of 10 Lm diameter, were probed using a wide-angle X-ray diffraction, small-angle X-ray scattering, transmission electron microscope, polarizing optical microscopy and light scattering. After crystallization had taken place at 80 degreesC, the PPCNs formed rod-like crystalline texture in the 10 mum length scale which consisted of the inter-fibrillar structure including gamma -phase crystallite caused by the reduction of the PP-MA chains mobility due to the intercalation of the PP chains in the space between silicate galleries and the narrow space surrounded by the dispersed clay particles. The intercalated PPCNs showed an enhancement of moduli compared with PP matrix without clay. The necessity of the intercalating degree of PP-MA chains on the enhancement of the mechanical properties are discussed.