MgO/N-doped active carbon (Mg/N-C) derived from sugarcane bagasse was prepared for the removal of methyl orange (MO). Mg/N-C composites presented the better adsorption capacity than that of active carbon and N-doped active carbon, of which the maximum adsorption capacity of 2-Mg/N-C-b2 for the MO removal is 384.61 mg g-1. The effects of MgO dosage, N-doped content, pyrolysis temperature, pH value, inorganic ions and solution temperature on the adsorption performance of Mg/N-C composites in the MO removal were investigated in detail. The pseudo-second order model and Langmuir isotherm model fitted well with the adsorption kinetics and isotherms of Mg/N-C. The rate-determining step was the boundary diffusion and intra-particle diffusion. The adsorption process of 2-Mg/N-C-b2 was a spontaneous and physisorption process.