Al2O3-based CoFe2O4 (CoFe2O4/Al2O3) as a catalyst was prepared to activate peroxymonosulfate (PMS) for degradation of sulfachlordpyridazine (SCP). In general, the catalytic performance of CoFe2O4/Al2O3 in activation PMS was demonstrated more effective than CoFe2O4. Several influence factors were inspected, including scavengers, PMS concentration, pH, anions, nature organic matter (NOM) and temperature. The oxidation of SCP fitted a pseudo-first-order kinetics model and was efficient with the pH from 5.00 to 8.00. The influence of scavengers demonstrated that SO4- played a more significant role than HO. in the oxidation process. The removal was strongly inhibited by adding NOM or HCO3-, and almost unaffected by adding NO3-, while chloride could enhance the degradation in the system. The increasing temperature greatly promoted the degradation of SCP. After four recycles, CoFe2O4/Al2O3 still showed preferable catalytic performance with 97.6% removal rate of SCP. Furthermore, the degradation mechanism was explored based on the XPS results. In the composit of CoFe2O4/Al2O3, Al2O3 had no additional catalytic performance but just as a matrix base. 2017 Elsevier B.V. All rights reserved.