A　one-pot　hydrothermal　method　was　proposed　for　the　synthesis　of　carbon　based　dots　(CDs)　with　high　quantum　yield　and　controllable　long-wavelength　photoluminescence　(PL).　The　PL　mechanisms　of　the　CDs　were　discussed,　and　a　common　model　has　been　proposed.　Furthermore,　the　obtained　CDs　showed　excellent　biocompatibility　and　high　PLQYs　(more　than　20%),　and　presented　great　potential　bio-applications.