Considering the frequent detection in environment and the potential threat to human health and ecoenvironment, achieving removal of sulfamerazine (SMZ) from the aquatic environment is of great significance. In this study, the magnetically separable manganese-iron oxides/activated carbon (Mn-Fe3O4/AC) was synthesized by simple co-precipitation method and was used to remove SMZ from solution. Doping manganese oxide could change the specific surface areas of the prepared materials, thus providing more active sites for adsorption and improving the adsorption capacity of Mn-Fe3O4/AC for SMZ (maximum adsorption capacity 146mg g-1). The kinetic and thermodynamic study showed that the adsorption of SMZ on Mn-Fe3O4/AC was endothermic and spontaneous, and followed the pseudo-second-order kinetics model and Langmuir model. Efficient removal of SMZ was attributed to varieties of noncovalent interactions between it and Mn-Fe3O4/AC, including electrostatic interactions, hydrogen bonds and π-π electron donor-acceptor interactions. In addition, SMZ could be degraded by oxidation via redox reactions. After six cycles of use, Mn-Fe3O4/AC still had good adsorption capability.