Nonisothermal crystallization and melting behavior of PP/nanoclay/CaCO3 ternary nanocomposite were investigated using different melt flow index (MFI) of PP, nanoclay and CaCO3 contents. The rate of crystallization was also studied using relative crystallinity as a function of temperature and time. The results show that the increase of MFI of PP and CaCO3 content in the prepared ternary nanocomposite shift the crystallization curve of PP to the higher temperature. However, increasing the content of nanoclay from 2 wt % to 6 wt % decreases the crystallization temperature possibly due to the restriction of molecular chain mobility. Further analysis of nonisothermal crystallization was carried out based on Avrami equation which the crystallization kinetic of prepared nanocomposite was evaluated. Except the significant variation in the heat of melting, the influence of these parameters on the melting behavior was much less than the crystallization process. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012