Hollow　mesoporous　tungsten　trioxide　spheres　(HMTTS)　have　been　synthesized　by　spray　drying　method　combined　with　proper　calcination　and　Ag/HMTTS　are　prepared　on　the　basis　of　a　silver　mirror　reaction.　HMTTS　are　composed　of　nanoparticles　with　diameter　of　20-70　nm.　The　accumulation　of　nanoparticles　generates　pores　with　the　mean　pore　size　of　about　45　nm.　The　formation　mechanism　of　hollow　mesoporous　structure　is　studied　in　this　work.　Ag　in　WO3　narrows　the　band　gap　and　derceases　the　recombination　possibility　of　the　photogenerated　electron　hole　pairs,　which　enhance　photocatalytic　activity　of　Ag/WO3　composites.　The　degradation　rate　of　methylene　blue　is　98.16%　under　UV　light　illumination　for　75　min　and　49.07%　under　visible　light　irradiation　for　150　min　by　Ag/WO3　composites.