The flow induced Nano orientation on crystallization of Nano composites has always been a challenging issue. The main objective of the present work was to study the crystallization behavior of PP/MWCNT Nano composites by using rheological technique. In this study Nano composites PP/MWCNT melt blending method with mixing 20min, 190 0C & 90rpm in combination with different percentages of carbon nanotubes were prepared. To the incorporation of nanoparticles, in all cases 10Phr, PP-g-MA was used. Viscoelastic studies and sample’s crystallinity is done by the rheological techniques and tools of RMS and check dispersion and orientation distribution of the nanoparticles with a transmission electron microscope TEM. The results of temperature sweep tests (G’-T) showed a Nano induced increase in crystallization temperature which could be attributed to nucleation mechanism. That, this results were found to be agreement with DSC results. However, the flow induced Nano orientation did not have a considerable effect on changing the crystallization temperature. The isothermal rheological measurements (G’-time) performed on the sample under different shear rate or shearing time showed a significant increasing effect on crystallization rate but, with little total effect on the total crystallinity. This results could be explained in terms of amplification effect of shear induced orientation.