Abstract: Nano-zirconia (nano-ZrO2) was used as nucleation agent to improve the properties of linear low-density polyethylene (LLDPE). The behaviors of nano-ZrO2/LLDPE composites contenting various mass fractions of ZrO2 were investigated by means of differential scanning calorimetry (DSC) in the non-isothermal crystallization process. Jeziorny and Mo methods were used to analyze the parameters of non-isothermal crystallization kinetics. The activation energies in crystallization were evaluated by Kissinger and Takhor methods. The results demonstrate that the addition of ZrO2 slowed the crystallization rate of LLDPE and restrained the crystal growth. The addition of 10wt% nano-ZrO2 decreased the activation energy of LLDPE, which improved the heterogeneous nucleation during non-isothermal crystallization process of LLDPE. The activation energy of LLDPE increased and heterogeneous nucleation was not obvious for LLDPE with 5wt% of nano-ZrO2.