Phosphorescent materials show good application prospects in optical sensing, biological imaging, anti-counterfeiting and other fields because of their excellent afterglow characteristics, simple preparation, low toxicity and other advantages. Large amounts of pickled skin (PS) offcut are produced easily during the leather making and abandon of leather products. It has been proved that PS can be used to prepare carbon dots (CDs) for anti-counterfeiting. The development of phosphorescent carbon dots (P-CDs) is expected to enrich the types of carbon dots with pickled skin and improve the anti-counterfeiting effect. In this paper, P-CDs were prepared by a one-step pyrolysis method using PS as carbon source and boric acid as boron source. The effects of PS content, reaction pH, reaction temperature and reaction time on the afterglow time of P-CDs were investigated. The results show that when the mass ratio of boric acid to PS is 3:0.12, the reaction pH is 7, the reaction temperature is 225 ℃, and the reaction time is 7.5 h, the afterglow time of P-CDs is the longest, reaching 12 s. The material has an emission wavelength of 520 nm, corresponding to a bright green afterglow. It is found that the average particle size of P-CDs is about 4.42 nm, which has a typical graphite structure. Boron atoms are successfully incorporated into the P-CDs to form C-B, B-O conjugate chain structure, which stabilizes the triple excited state and prolongs the afterglow time. It presents potential application value in the field of anti-counterfeiting and information encryption.