In this work, a series of Ag/AgCl@ZIF-8 modified g-CN composites were synthesized and used to degrade levofloxacin (LVFX) in water under visible light irradiation with the assistant of peroxymonosulfate (PMS). The morphologies and physicochemical properties of the materials were characterized by SEM, TEM, XRD, XPS, FTIR, and DRS technologies. The results of photocatalytic experiments showed that in the presence of PMS, the degradation rate of LVFX reached 87.3% in 60min. Furthermore, factors affecting photocatalytic efficiency such as the concentration of PMS, photocatalyst dosage and different pH values were investigated. The degradation products of LVFX were analyzed by LC-MS and the degradation pathway was inferred. Active species trapping experiments indicated that O, h and SO played important roles in the degradation process in the presence of PMS and the possible degradation mechanism was put forward. This work provides a photocatalyst system that is beneficial to the separation of photogenerated carriers and demonstrates the great potential of PMS-assisted photocatalysis in the purification of organic pollutants.