-50　nm　BiOBr　nanoplates　were　first　fabricated　by　aqueous　precipitation　method.　Then　ultralong　α-Bi2O3　microrods　(-200　μm)　were　successfully　synthesized　by　applying　phase-transformation　route　with　produced　BiOBr　nanoplates　as　precursor　under　calcination　condition.　The　phase-transformation　from　BiOBr　to　α-Bi2O3　via　Bi24O31Br10　intermediate　were　studied　by　differential　thermogravimetric　analysis　(TGA),　X-ray　powder　diffraction　(XRD),　scanning　electron　microscope　(SEM),　and　UV-Vis　diffuse　reflectance　spectra　(UV-Vis　DRS).　It　reveals　that　BiOBr　nanoplates　are　not　thermostable.　Br　element　in　BiOBr　compound　was　gradually　released　during　calacnation　process.　With　the　loss　of　Br,　BiOBr　began　to　transform　to　plate-like　Bi24O31Br10　at　around　600℃　and　the　produced　Bi24O31Br10　totally　converted　to　ultralong　α-Bi2O3　microrods　at　800℃.　It　could　provide　a　simple　and　effective　method　to　fabricate　ultralong　α-Bi2O3　microrods.　©　2015,　Chinese　Ceramic　Society.　All　right　reserved.