The nonisothermal crystallization kinetics of polypropylene (PP) and polypropylene／organicmontmorillonite (PP／Mont) nanocomposite,which was prepared by melt intercalation,was studied by means of differential scanning calorimetry (DSC)．The modified Avrami theories of Jeziorny,Ozawa and Mo were used to analyze the data of DSC．The result showed that both the Jeziorny and Mo methods could describe this system very well,but the Ozawa analysis failed．The values of Zc and n increased with increasing cooling rate,and the values of Zc and n of PP／Mont nanocomposite were higher than those of PP at the same cooling rate．The value of F(T) increased,and the value of a had no significant change with increasing degree of crystallinity for PP and PP／Mont nanocomposite,respectively. The values of F(T) of PP／Mont nanocomposite were lower than those of PP at the same degree of crystallinity．The value ofa was 1.04,1.40 or so for PP and PP／Mont nanocomposite,respectively．The activation energies have been evaluated by Kissinger method to be 189.37 kJ／mol and 155.69 kJ／mol for the nonisothermal crystallization of PP and PP／Mont nanocomposite,respectively．The addition of organic montmorillonite decreased the activation energy of crystallization of PP,which could be used as nucleating agent during nonisothermal crystallization process of PP．