Nanocrystalline powders of w(Al2O3)=95%, w(TiO2)=3%, and w(SiO2)=2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D. C. plasma was used to spray the agglomerated nanocrystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10-90)μn. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional micros Nanocrystalline powders of w (Al2O3) = 95% w (TiO2) = 3% and w (SiO2) = 2% were reprocessed into agglomerated particles for plasma spraying by by consecutive steps of ball milling, slurry forming, spray drying , and heat treatment. DC plasma was used to spray the agglomerated nanocrystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10-90) μn. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Both conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional micros