Abstract: High energy density plasma technique(HEDP) was applied to surface treatment of Fe₃Al. A micro-crystalline layer with grain sizes between 10 and 100nm was obtained. Isothermal oxidation at 1000℃ in air for cast Fe₃Al before and after micro-crystallizing was studied. The results showed that for the micro-crystalline Fe₃Al,(1) a micro-crystalline oxide scale formed during oxidation;(2) the plasticity and adhesion of oxide scale was remarkably improved;(3) the oxidation rate was decreased;(4) the oxidation kinetics obeyed the forth power equation law.