Abstract: Nitrogen-doped carbon quantum dots (N-CDs) were synthesized by low temperature reflux method with ascorbic acid and ethylene diamine as raw materials. Berberine hydrochloride could quench the fluorescence of the N-CDs with specificity.Based on the fact,a method was proposed for berberine hydrochloride determination with N-CDs as a fluorescent probe. In Tris-HCl buffer solution of pH 7.40, linear relationship between quenching values of N-CDs fluorescence intensity and concentrations of berberine hydrochloride was kept in the range of 5.0×10^-7-4.0×10^-5mol·L^-1, with detection limit (3s/k) of 2.0×10^-7mol·L^-1. The proposed method was applied to the analysis of tablets of berberine hydrochloride, giving values of recovery of 99.2%, 103%. The dynamic quenching between the N-CDs and berberine hydrochloride was proved by the changes of the fluorescence lifetime as well as the absorption spectrum and the effect of temperature on the quenching constants.