The isothermal crystallization kinetics for four impact propylene eopolymers with different ethylene contents at different crystallization temperatures were investigated by employing differential scanning calorimetry (DSC)．The results indicated that the kinetics of isothermal crystallization for all the samples was fitted quite well by the Avrami equation within the selected crystallization temperature range(126～130℃)．With the increase of ethylene content in impact propylene copolymers

the Avrami exponent (n) did not vary significantly with temperature．The crystallization of impact pmpylene copolymer may involve heterogeneous nucleation with the controlled 3-dimensional diffusion Crystallization activation energy (△E) of four impact propylene copolymers ranged from about 279.5 to around 343.1 kJ/mol As the ethylene content increased

the crystallization activation energy increased The results clearly indicate the significant influence of the ethylene content on the crystallization activation energy．The results of CRYSTAF test showed

along with the increment of the ethylene content

an increase in the tacticity of propylene homopolymers and decreases in the isotacticity、long crystallizable sequence content.