The carbon dots solution was prepared by the microwave method using citric acid and polyethylene glycol 200 as raw materials, which was characterized by laser dynamic light scattering, XRD, UV, TEM and fluorescence spectrophotometer. The experimental results show that the carbon dots produced are approximate spherical with better dispersity and without reunion phenomenon, and their sizes are about 5 nm. At the optimum excitation wavelength of 363 nm, the emission wavelength is 418 nm. With the increase of temperature, the emission peak position of the carbon dots solution does not move, but the intensity of fluorescence declines significantly. There is a good linear relationship between the fluorescence intensity and temperature, R2=0.9895. The carbon dots sensitive to temperature are expected to be used in some devices of fluorescent material of displaying and the measurement of surface temperature.
