Abstract: An oxide dispersion strengthened(ODS) ferritic steel with nominal composition of Fe-12Cr-2.5W-0.25Ti-0.2V-0.4Y₂O₃ (0.4Y₂O₃/12Cr, mass fraction, %) was produced by using ethylene diamine tetraacetic acid(EDTA) complex method to add Y₂O₃ particles to an argon atomized steel powder, followed by hot isostatic pressing, forging and heat treatment. The formation process and behavior of oxides in the composite powder, the 0.4Y₂O₃/12Cr steels in hot isostatic pressing and under forged conditions were characterized by using SEM, FE-SEM and XRD. The results show that the oxides formation mechanisms of 0.4 Y₂O₃/12Cr steel by EDTA complex method are complex thermal decomposition mechanism, interfacial reaction mechanism, and reprecipitation mechanism. The fine and uniform oxide dispersoids distributtion in the ferrite matrix could be obtained by choosing appropriate parameters and mechanical dispersing effect.