We　herein　prepared　the　boron-doped　graphitic　carbon　nitride　(B-g-C3N4)　nano-sheets　with　1-5　monolayers　and　50-200　nm　size　via　heating　the　mixture　of　melamine　and　boron　oxide.　We　demonstrated　that　the　prepared　thinlayer　B-g-C3N4　nano-sheets　have　a　high　and　stable　photo-catalytic　activity　for　degrading　various　organic　dyes　with　a　high　speed　and　efficiency　under　visible　light　irradiation.　In　the　presence　of　2　mg/mL　of　B-g-C3N4　nanosheets,　Eosin　Y　(EY,　heterocyclic　dye),　Rhodamine　B　(RhB,　triarylmethane　dye),　Methylene　blue　(MB,　thiazide　dyes)　and　Methyl　orange　(MO,　Azo　dyes)　can　be　completely　degraded　within　5,　10,　20　and　60　min　respectively　under　visible　light　irradiation　follow　the　first-order　kinetics.　The　possible　route　and　intermediate　products　of　various　dyes　during　photo-degradation　over　B-g-C3N4　nano-sheets　were　also　investigated.　In　comparison　with　other　g-C3N4　or　g-C3N4-based　materials,　the　prepared　thin-layer　B-g-C3N4　nano-sheets　have　much　higher　photocatalytic　activity　and　can　be　used　for　visible　light-driven　degrading　various　organic　dyes.　The　success　of　this　study　provides　a　promising　method　for　economical,　rapid　and　environmental-friendly　treatment　of　dye-contaminated　water.