To achieve complete removal of persistent organic pollutant from water system, an efficient, stable, magnetic and low-energy sulfate radical-based advanced oxidation process (SR-AOPs) is in desirable to be established. In this work, magnetic trimetallic oxides Co3MnFeO6 nanoparticles were successfully synthesized and utilized as novel heterogeneous catalysts to activate peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ), a recalcitrant organic pollutant. In the degradation tests, Co3MnFeO6/PMS system showed excellent performance that 99.2% of CBZ could be removed at a relative shorter time (30 min) and in a wider pH range from 3 to 10. More in-depth investigation found that synergistic effects between Co, Mn and Fe in Co3MnFeO6 catalyst were responsible for the efficient generation of sulfate radical from PMS activation. And the roles of Co, Mn and Fe in synergistic effect were identified as: the redox cycles of Co and Mn mainly worked for the activation of PMS, and Fe mainly provided magnetism for Co3MnFeO6 catalyst as well as the adsorption site for PMS and CBZ. Moreover, it was found that Co3MnFeO6 catalyst maintained high activity and robust magnetism during repeated batch experiments. Even in real wastewater samples (municipal wastewater, tap and river water), Co3MnFeO6/PMS system was capable of high activity for CBZ removal, indicating that Co3MnFeO6/PMS system possessed promising potential in practical applications. The possible CBZ degradation pathways were also proposed based on the detected intermediates. This Co3MnFeO6/PMS system may provide some new inspirations for the construction of multiple metal-based catalysts in AOPs.