Abstract: The non-isothermal crystallization behaviour of coal gangue filled polypropylene(PP) composites with different coal gangue contents was investigated using differential scanning calorimetry (DSC), and then was treated using Jeziorny equation. And the diffusion activation energy of composites during non-isothermal crystallization was calculated by Kissinger method. The results show the crystallization temperature of composites was higher than that of pure PP at the same cooling rate. Crystallization rate of composites had a decline trend after an initial ascent with the increase of coal gangue content and reached a peak while coal gangue content was 15wt.%. The diffusion activation energy of PP/coal gangue composites first increased and then decreased along with the increase of the coal gangue content and reached a peak while coal gangue content was 5wt.%.