Abstract: PTFE/nanoAlN composites were prepared by cold moulding and sintering in air. Effects of nanoAlN content on the mechanical properties and crystallization of the composites were studied. It showed that mechanical properties and the degree of crystallization of composites first increased and then decreased with increasing weight percentage of nanoAlN. The nanoAlN exhibited a remarkable heterogeneous nucleation activity and the crystallization rate was enhanced. However, the effect of nanoAlN content on the crystallization temperature was not obvious.