Carbon　nitrides　form　a　series　of　polymer　semiconductors　popular　in　photocatalysis.　In　the　course　of　photoresponse,　the　separation　of　light-induced　electron-hole　pairs　is　one　of　the　critical　factors　that　affect　the　conversion　rate　from　photoenergy　to　chemical　substance.　Exciton　binding　energy　(Eb)　is　treated　as　a　classical　parameter　to　evaluate　the　barrier　of　exciton　dissociation.　In　this　work,　we　study　the　electronic　and　optical　nature　of　two　specific　members　of　the　carbon　nitride　family,　polymeric　carbon　nitride　(melon)　and　crystallized　poly(triazine　imide)　(PTI/Li+Cl-)　by　employing　the　photoluminescence　spectra　and　density　functional　theory　(DFT)　calculations　based　on　the　Wannier-Mott　exciton　module.　The　results　of　self-consistent　GW　computation　were　applied.　The　measurement　of　photoluminescence　spectra,　by　which　exciton　binding　energies　are　estimated,　is　likewise　discussed.　Generally,　compared　with　the　results　calculated　by　GW-BSE,　the　DFT　results　based　on　the　Wannier-Mott　model　are　closer　to　the　experimental　values.　From　a　materials　perspective,　on　the　other　hand,　the　exciton　binding　energy　of　the　melon　is　lower　than　that　of　PTI/Li+Cl-.