Oxide dispersion strengthened (ODS) steels are the most fascinating candidate materials for high temperature nuclear applications. ODS steel with nominal composition of Fe-14Cr-2W-0.2V-0.07Ta-10Y(2)O(3) was prepared by mechanical alloying (MA). The morphology and structure evolution of the alloy powders and Y2O3 nanoparticles during MA and following annealing were studied in this work. Results show that the Y2O3 nanoparticles changed into flake polygons and rods from the nearly spherical shape after MA. The lattice structure of Y2O3 was damaged at the initial stage of MA, and amorphous areas appeared during this process. In the subsequent annealing procedure, the flake polygon structure of Y2O3 was gradually transformed into long strips, and then separated to form a nearly spherical shape. Y2O3 particles presented a more stable structure and the crystallization procedure of Y2O3 particles were completed more thoroughly at higher annealing temperature. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.