The effect of SEBS-g-MAH on the isothermal crystallization behavior of LLDPE was studied by using DSC.The crystalline morphology of the LLDPE and LLDPE/SEBS-g-MAH blends was examined by using polarized optical microscope (POM）.The results demonstrated that due to partial destruction of crystal region，the crystallization rate of LLDPE decreased and the activation energy of crystallization increased with addition of SEBS-g-MAH.Addition of elastomer played an inhibition effect on crystal growth of LLDPE，and the grain size decreased.The isothermal crystallization process was described by the Avrami equation and the Avrami exponent n was related with crystallization temperature.The half crystallization time (t1/2) of LLDPE/SEBS-g-MAH was much longer than that of pure LLDPE and the value of kn decreased with increasing crystallization temperature.The σe，interfacial free energies per unit area perpendicular to LLDPE chains，of pure LLDPE and LLDPE/SEBS-g-MAH blends were calculated with the Hoffman theory.The result showed that σe of pure LLDPE was 0.136 J·m-2 and σe of LLDPE/SEBS-g-MAH blends increased by adding SEBS-g-MAH.