To　improve　the　photocatalytic　performance　of　carbon　nitride　(g-C3N4),　a　flower-shaped　COCN/ZIS　composite　was　synthesized　by　growing　ZnIn2S4　(ZIS)　onto　structurally　defective　g-C3N4　(COCN)　nanosheets.　The　experimental　results　indicate　that　the　prepared　photocatalyst　has　excellent　photocatalytic　performance　for　the　degradation　of　methylene　blue　(MB),　with　an　apparent　rate　constant　of　0.0661　min(-1),　which　is　approximately　6.89,　6.06　and　7.39　times　greater　than　that　of　g-C3N4　(0.0096　min(-1)),　COCN　(0.01091　min(-1))　and　ZIS　(0.00895　min(-1)),　separately.　The　improvement　in　the　photocatalytic　performance　of　COCN/ZIS　can　be　attributed　to　the　defect　structure　of　COCN　and　the　well-matched　relationship　between　COCN　and　ZIS,　both　of　which　result　in　valid　photoinduced　charge　separation　and　migration.　This　has　also　been　confirmed　by　the　synergy　coefficient　(3.33).　Furthermore,　the　total　organic　carbon　content　(TOC)　removal　rates　of　MB　and　wastewater　by　the　60-COCN/ZIS　composite　were　85.96　%　and　75.32　%,　respectively,　suggesting　that　the　resultant　catalyst　has　potential　application　in　the　photodegradation　treatment　of　MB.　Finally,　the　capture　experiments　and　electron　paramagnetic　resonance　analysis　show　that　center　dot　OH,　center　dot　O-2(-)　and　h(+)　species　are　generated　during　the　process,　among　which　center　dot　OH　plays　a　great　part　in　the　photodegradation　of　MB　by　the　COCN/ZIS　compound.