Aim: To synthesize a series of nitrogen-doped(N-doped)photo-luminescent carbon dots(CDs)and use them for bio-imaging.Methods: The one-pot hydrothermal method was designed using citric acid as the common carbon source and some amino acid as nitrogen source in the absence of any additional substances.Results and Conclusion: The brightest CDs doped by arginine with relatively high fluorescence quantum yield of 33.25%was selected for the sub-continuous study.And this arginine doped carbon dots showed good stability under the irradiation,variation of pH and oxidative-redox conditions.The low toxicity was demonstrated on different cell lines and living mice,which confirmed its applicability for bio-imaging.By taking advantage of cell uptaking ability to nanoparticles,this small and biocompatible carbon dots can be served as optical stain in cell imaging.Moreover,the bio-distribution of the small-sized water soluble CDs persuaded the CDs-Arg nanoparticles can be cleared from the body via the kidney-bladder pathway.Consequently,the results demonstrated that the CDs-Arg is a promising candidate for bio-imaging and drug-metabolism monitoring.