Based on the industrial production of non-oriented silicon steel,the rare earth(RE) treatment during the Ruhrstahl Heraeus(RH) refining process was studied.The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions.Furthermore,the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed.The results have shown that in the present work,the suitable RE metal additions are 0.6-0.9 kg/t steel.After the suitable RE treatment,the formation of AlN and MnS inclusions were restrained,and the aggregation,flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased.Meanwhile,the total oxygen concentration reached the minimum value and the desulfurization efficiency was optimal,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large. Based on the industrial production of non-oriented silicon steel, the rare earth (RE) treatment during the Rhrstahl Heraeus (RH) refining process was studied. Morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. The formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were. The results have shown that in the present work, the suitable RE metal additions are 0.6-0.9 kg / t steel. After the suitable RE treatment, the formation of AlN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased., while the total oxygen concentration reached the minimum value and the desulfurization efficiency was optimal, and the type of main inclusions were approximately spherical or elliptical spherical RE radicle inclusions whos e size was relatively large.