Based　on　the　hollow　ammonium　metatungstate　spheres　(HAMTS)　prepared　by　spray　drying　method,　hollow　mesoporous　WO3　spheres　were　synthesized　by　adjusting　calcination　temperature.　The　results　show　that　[H2W12O40](6-)　with　Keggin　structure　in　HAMTS　is　destroyed　in　the　temperature　of　417　to　439　degrees　C.　Apart　from　WO3,　a　small　amount　of　ammonium　ions　and　bounding　water　still　exist　in　the　form　of　(NH4)(0.06)WO3(H2O)(0.11)　in　the　sample　after　being　calcined　at　500　or　550　degrees　C.　Increasing　temperature　to　700　degrees　C　for　2　h,　hollow　mesoporous　WO3　spheres　can　be　obtained.　The　mechanism　for　the　formation　of　hollow　mesoporous　structure　is　proposed　as　follows.　Due　to　the　difference　of　the　subgrain　orientation　and　the　preferred　[002]　growth,　narrow　particles　are　crystallized　by　integrating　HAMTS　subgrains　during　the　heat　treatment　process,　leading　to　the　mesoporous　structure　on　the　surface　of　hollow　WO3　spheres.　When　the　sample　is　calcined　at　800　degrees　C　for　2　h,　the　channels　between　the　grains　disappear.　The　photocatalytic　degradation　rate　of　methylene　over　blue　hollow　mesoporous　WO3　spheres　is　65.9%　under　the　illumination　of　500　W　high　pressure　mercury　arc　for　150　min.