Antibiotics in aquatic environments present a serious threat to the ecological environment and human health. Activation of carbon-catalyzed persulfate is a prospective approach for oxidizing antibiotics. There is a pressing need for inexpensive carbon catalysts of high quality. In this study, biochar (BC) modified by Fe, Mn and Fe@Mn was employed to activate peroxymonosulfate (PMS) to degrade carbamazepine (CBZ) in water. The surface of Fe@Mn BC had a dense, stalactite-like morphology comprising a square chassis that was elliptical. The catalyst Fe@Mn-BC possessed the optimal degradation effect (99%) on CBZ at 100 min. Electron paramagnetic resonance spectroscopy and the quenching spectrum suggested that O2- and 1O2 contributed to CBZ degradation. Biochar (BC) modified by Fe@Mn was employed to activate PMS to degrade CBZ in water. The surface of Fe@Mn-BC presented a dense, stalactite-like morphology. The catalyst Fe@Mn-BC had an optimal degradation effect (99%) on CBZ at 100 min.