DyVO4/iodine　modified　graphitic　carbon　nitride　(DyVO4/g-C3N4I)　composite　semiconductors　with　different　weight　percents　of　DyVO4　were　successfully　synthesized　by　a　facile　heating　method,　and　characterized　by　X-ray　diffraction　(XRD),　X-ray　photoelectron　spectroscopy　(XPS),　transmission　electron　microscopy　(TEM),　UV-vis　diffuse　reflection　spectroscopy　(UV-vis　DRS),　photoluminescence　(PL)　and　electron　paramagnetic　resonance　(EPR)　spectra,　N2　adsorption-desorption　analysis　and　photo-electrochemical　measurement.　The　resulting　DyVO4/g-C3N4I　semiconductor　with　a　suitable　weight　percents　of　6.3%　DyVO4　showed　the　highest　visible-light　photoactivity,　and　its　degradation　ratio　for　methylene　blue　was　more　than　1.8　time　higher　than　that　of　DyVO4,　g-C3N4　and　g-C3N4I.　The　H2　evolution　rate　of　6.3%　DyVO4/g-C3N4I　was　10.6,　4.7　and　1.7　times　higher　than　that　of　DyVO4,　g-C3N4　and　g-C3N4I,　respectively,　while　still　having　excellent　reusability　and　stability.　The　obviously　enhanced　photoactivity　of　6.3%　DyVO4/g-C3N4I　is　mainly　ascribed　to　the　fact　that　the　proper　DyVO4　modified　g-C3N4I　increase　its　specific　surface　area,　decrease　band-gap　energy,　enhance　absorption　in　the　400-700nm　region　and　promote　efficient　separation　of　photo-generated　carriers.　The　mechanism　on　the　improvement　of　visible-light　photoactivity　is　discussed.　©　2015　Elsevier　B.V.