A　series　of　flower-like　BiOBrxI1-xcomposite　microspheres　were　prepared　by　solvothermal　method.　The　thermostability　of　the　microspheres　and　the　effects　of　calcination　temperature　on　their　phase,　morphology,　light　absorption　and　photocatalytic　performance　in　degradation　acid　orange　were　investigated　by　X-ray　diffraction　(XRD),　thermal　gravity　(TG)　analysis,　N2-physical　adsorption,　scanning　electron　microscopy　(SEM),　Fourier　translation　infrared　spectroscopy　(FT-IR),　and　UV-Vis　diffuse　reflectance　spectroscopy　(DRS).　The　results　show　that　the　thermostability　of　the　BiOBr0.25I0.75is　lower　than　BiOBr　and　slight　higher　than　BiOI.　During　calcination,　with　the　loss　of　I　element,　new　Bi5O7I　appeares.　The　compounds　are　mainly　composed　of　Bismuth　oxygen　bromide　after　500.　The　spherical　structure　is　destroyed　when　calcined　above　450,　and　specific　surface　area　decrease　rapidly.　The　photocatalytic　activity　of　BiOBr0.25I0.75and　BiOBr0.5I0.5is　higher　than　BiOBr　and　BiOI.　After　calcination,　activity　appeared　obvious　decline.　The　destruction　of　morphology　and　composition,　and　the　loss　of　surface　area　which　attributed　to　high-temperature　calcination　would　cause　the　decrease　in　photocatalytic　performance.　©,　2015,　Chinese　Ceramic　Society.　All　right　reserved.