Fluorescent carbon quantum dots (CQDs) were prepared from chitosan by one-step hydrothermal method. The effects of reaction conditions such as mass concentration of chitosan, temperature and time on surface functional group and yield were investigated. The morphology, structure and properties of samples were characterized by TEM, FTIR, XRD, UV-Vis and PL spectra. The application in the field of anti-counterfeiting was explored. The results showed that the prepared CQDs had complete structure and high yield under the conditions of mass concentration of chitosan of 10 g/L, temperature of 180 ℃, and time of 12 h. The spherical CQDs nanoparticles had a diameter of about 36.2 nm, accompanied by hydroxyl and amino functional groups on the surface. In addition, CQDs exhibited strong absorption peaks at 293 and 330 nm, which show a blue fluorescence. The fluorescence quantum yield was about 39.8%. After they were made into ink for ink-jet printing, the encrypted pattern could be "visible" and "hidden" effectively under natural light and UV light, indicating the ink prepared from CQDs has excellent anti-counterfeiting effect.