The magnetic Fe3O4-nanographene platelets (Fe3O4-NGP) platelets composites with various concentrations of nanographene platelets were used as a catalyst for the removal of methylene blue in aqueous solution. The adsorption and sonocatalytic performances were evaluated using methylene blue in aqueous solution. The effect of NGP content in the Fe3O4-NGP, pH and initial concentrations of methylene blue were investigated. Compared in the dark Fe3O4-NGP shows faster and higher removal efficiency by the adsorption and sonodegradation. It could be concluded that synergy of adsorption and sonodegradation have a significant progress for removal of methylene blue compared with adsorption alone. The removal of methylene blue follows the order adsorption-sonocatalysis > sonocatalysis > adsorption. The predominant oxidative species for degradation of methylene blue was identified to be hydroxyl radicals and holes.