A　novel　hollow　network　magnetic　Fe3O4/SiO2/meso-TiO2　(FSmT)　composite　microsphere　photocatalyst,　with　network　Fe3O4　nanorods　as　a　magnetic　layer,　a　dense　SiO2　layer　as　an　electronic　barrier,　and　a　mesoporous　TiO2　as　the　active　layer,　was　synthesized　by　sol-gel　and　hydrothermal　process.　The　as-synthesized　FSmT　microspheres　possess　a　high　specific　surface　area　(122m(2)/g),　a　large　mesoporous　size　(diameter=5.47nm),　and　pore　volume　(0.27cm(3)/g).　Further,　the　photocatalytic　activity　of　the　FSmT　microspheres　for　methyl　orange　degradation　was　demonstrated　and　the　degradation　rate　of　methyl　orange　could　reach　up　to　93.5%　after　1h　under　UV　light.　The　good　photocatalytic　activity　was　attributed　to　the　hollow　network　and　mesoporous　composite　structures.　The　FSmT　microspheres　could　be　separated　conveniently　and　well　redispersed　for　further　reuse　because　of　their　excellent　magnetic　property　(Ms=11.4emu/g).　Graphical　Abstract　Schematic　diagram　for　the　photocatalytic　reaction　of　methyl　orange　solution　with　the　FSmT　microspheres.　[GRAPHICS]　.　Highlights.　The　hollow　structure　of　the　composite　microspheres　is　a　warehouse　for　methyl　orange　and　the　channel　of　mesoporous　TiO2　is　as　a　reactor　for　photocatalytic　reaction..　The　photocatalytic　reaction　with　TiO2　began　as　methyl　orange　in　warehouse　entered　the　mesoporous　channel..　As　the　reaction　continues,　more　and　more　methyl　oranges　enter　the　pore　canal　and　react　successively　until　the　end　of　the　reaction.