XRD, TEM, SEM and OM techniques are used to investigate the cyclic oxidation behavior of Ni-20Cr alloys prepared by mechanical alloying (MA ) and conventional casting (CA ) at 1000 ℃ in air. It is found that a compact Cr2O3 scale is formed with a very good adhesion for the mechanically alloying Ni-20Cr alloy, even after a cyclic oxidation at 1000 ℃for 200 h, but a slight scale spallation is observed. For the conventional casting Ni-20Cr alloy, a complex scale of NiO/NiCr2O4 is formed, and a severe scale spallation is observed with a obvious mass decrease after a cyclic oxidation at 1000 ℃ for 200 h. The results show that the MA Ni-20Cr alloy exhibits a better cyclic oxidation resistance than the CA Ni-20Cr alloy owing to the fact that the grain refinement can significantly promote the formation of Cr2O3 scale and enhance the adhesion to the scale by the thermal stress reduction and release