A series of phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph) films which possesses crosslinking reaction combined with crystallization behavior had been prepared successfully, and their crystallization and crosslinking degree can be controlled by altering the heat-treating temperature. With heat-treating temperature increasing from 200 oC to 280 oC, the crystallization of the PEN-Ph films increased greatly, which could be proved by the DSC and XRD analysis results. Besides, because of the crosslinking reaction of the phthalonitrile groups at high temperature to form phthalocyanine ring, the crosslinking degree calculated by Soxhlet extraction method also increased as the heat-treating temperature increased from 200 oC to 280 oC. Moreover, when the heat-treating temperature reached to 300 oC, although the crystallization has little change compared with the sample with heat-treating temperature at 280 oC, the crosslinking degree increased dramatically. With further increasing in heat-treating temperature, the crosslinking degree continue to increase, whereas the crystallization decreased substantially. The phenomenon that the crystals were not melting completely at higher temperature could be explained as follows. The phthalonitrile groups on the PEN-Ph crystals can react with the phthalonitrile groups in the matrix resin to form phthalocyanine ring, so that the PEN-Ph crystals can be embedded in the crosslinked matrix, resulting in the improvement of the crystals thermal stability. Therefore, a novel PEN-Ph film with high crystallization and crosslinking degree can be obtained by appropriate temperature and appropriate time treatment.