Abstract: Wear is one of main material failure forms.Nanostructured WC-Co coating technology is expected to become a key technology to solve wear-resistance of critical components in largescale equipments.Nanostructured and ultra-fine WC-17Co coatings were prepared by plasma spraying.The wear behavior at elevated temperature and failure mechanism were investigated.The results indicate that wear resistance at high temperature of the nanostructured WC-17Co coating is much better than that of the ultra-fine coating. The wear mechanism is different between the ultra-fine coating and the nanostructured coating, which low-ductility cracking and abrasive wear following with adhesive wear predominates in ultra-fine coating, and adhesive wear following with abrasive wear predominates in nanostructured coating.