The polypropylene/aluminum nitride (PP/AlN) thermal conductivity composites were prepared by compression moulding method. Results revealed that the thermal conductivity of the composites were increased with the increasing AlN, and the thermal conductivity of composites was 1.84W/mk filled with 50vol% modified AlN. Both the tensile and impact strength of the composites increased firstly, but decreased with excessive addition of AlN. For given AlN loading, the surface modification of AlN exhibited a positive effect on the thermal conductivity. Meantime, the grafting of PP could increase the thermal conductivity of the composites compared with pure PP. And the addition of AlN did not change the crystal form of PP, but decrease the crystallinity of the composites.