In this paper,phosphorus doped carbon dots(P-CDs) were prepared by a self catalysis method with diphosphorus pentoxide and citric acid as raw materials.The P-CDs were characterized by transmission electron microscopy,Fourier transform infrared spectroscopy,X ray photoelectron spectroscopy,UV-visible absorption and fluorescence spectrometry.Results showed that the sizes of P-CDs mainly ranged from 5.0 nm to 10.2 nm,and on the surfaces of which existed hydroxyl,carboxyl and phosphorous groups.A novel method was developed for the sensitive and selective detection of hyperin(HP) based on the phenomenon that HP could quench the fluorescence of P-CDs.Under the optimum conditions,a good linear relationship was obtained between the fluorescence quenching efficiency(IF0/IF) and the concentration of HP in range of 0.22-55 μmol/L with a detection limit of 78 nmol/L.The method was successfully applied in the determination of HP in fufangmuji granules with recoveries of 93.3%-107% and relative standard deviation of 1.5%-1.7%.