A　kind　of　graphitic　carbon　nitride　(TSC−550)　with　high　polymerization　degree　and　improved　surface　property　was　prepared　by　a　new　precursor　of　thiosemicarbazide.　The　sulfur　motif　and　high　nitrogen　content　in　thiosemicarbazide　promoted　the　polymerization　of　thiosemicarbazide　to　form　graphitic　carbon　nitride　framework　with　high　degree　of　polymerization,　which　significantly　influenced　the　electronic　structure　and　surface　chemical　properties.　TSC−550　possessed　a　narrow　bandgap　of　2.19　eV　that　facilitated　the　utilization　of　visible　light,　and　possessed　a　less　positive　charge,　acidic　surface　that　resulted　in　enhanced　hydrogen　adsorption　ability　in　water　solution,　which　promoted　the　H2　evolution　kinetics.　In　addition,　the　extended　π-conjugated　electronic　system　promoted　the　separation　and　migration　of　photo-generated　charge　carries　in　plane　of　TSC−550　framework,　as　well　as　the　increasing　interlayer　C–N　interactions　in　TSC−550　created　conductive　paths　across　the　layers　to　tunnel　interlayers　for　rapid　electron　transportation.　As　a　result,　TSC−550　nanosheets　showed　excellent　photocatalytic　H2　production　activity,　the　AQY　achieved　36.4%　at　425　nm.　©　2021