In　this　paper,　a　method　for　preparing　polymeric　carbon　nitride/TiO2　(PCN/TiO2)　with　NH4Cl　as　template　is　proposed.　Comparing　with　PCN　prepared　with　conventional　methods,　the　specific　surface　area　of　PCN/TiO2　is　higher,　which　also　improves　the　photocatalytic　performance.　The　structure　and　evolution　of　samples　were　explored　via　FT-IR,　XRD,　SEM,　TEM,　BET　and　XPS　in　order　to　analyze　the　reaction　mechanism　of　PCN/TiO2.　In　the　meantime,　the　electron-hole　separation　efficiency　and　energy　band　structure　were　explored　by　PL　and　UV-Vis　spectra.　In　addition,　the　RhB　degradation　mechanism　and　electrons-holes　transport　path　of　PCN/TiO2　was　analyzed　by　degradation　experiments　and　EPR.　The　results　show　that　the　NH4Cl　which　is　the　template　was　decomposed　after　calcination,　therefore　PCN　showed　the　porous　morphology.　The　compound　of　PCN　and　TiO2　formed　heterojunction,　which　can　effectively　promote　the　electron-hole　separation　rate　to　improve　the　photo　catalytic　efficiency.　The　PCN/TiO2(2.5:1)　was　found　to　have　the　best　dye　degradation　efficiency　and　the　degradation　rate　of　RhB　could　reach　83.81%　within　150　min.　During　the　degradation　of　RhB,　the　active　substances　are　h+,　center　dot　OH　and　center　dot　O-2(-)　and　the　mechanism　of　electron-hole　transmission　is　Type-Z　transport　mechanism.