Carbon　quantum　dots　(CQDs)　is　a　promising　material　for　photosensitization　applications　but　substantially　suffers　from　the　tedious　product　separation　in　solution　and　poor　photosensitive　efficiency　in　the　visible　light　range.　Herein,　a　facile　and　efficient　hydrothermal　method　is　utilized　to　assemble　nitrogen-doped　CQDs　(NCQDs)　onto　graphene　aerogel　(GA)　for　reduction　of　toxic　Cr　(VI)　in　aqueous　solution　under　visible　light　illumination.　The　photoactivity　results　suggest　that　GA　skeleton　endows　NCQDs　with　a　strongly　enhanced　photoactivity　compared　to　that　over　blank　NCQDs.　Photoelectrochemical　results　demonstrate　that　the　introduction　of　GA　skeleton　facilitates　more　efficient　separation　and　transfer　of　photogenerated　charge　carriers　under　visible　light　irradiation.　Moreover,　as　compared　with　N-free　counterparts,　the　broadened　light　absorption　of　NCQD　resulting　from　the　ameliorated　nanocrystallinity　and　the　nitrogen　dopant　in　graphitic　structure　play　an　important　role　in　the　reduction　of　Cr　(VI)　reaction　under　identical　conditions.　It　is　believed　that　this　work　could　extend　the　promising　applications　of　CQDs　as　an　efficient　visible-light-responsive　photosensitizer　for　water　purification　and　beyond.