Recently,carbon dots(CDs)have drawn increasing attention,owing to exceptional advantages such as high optical absorption,strong and tunable photoluminescence,chemical stability,good biocompatibility and low toxicity [1].Most of the researchers are interested in discussing the synthesis process,only a few to explore the impact of preparation methods on CDs.In this paper,based on two kinds of methods,carbon dots(CD-1,CD-2)with high fluorescence quantum yield were prepared from citric acid via microwave and hydrothermal treatment respectively.We used many characterizations to study the character of the CD-1 and CD-2,as present in the Table1.