Previous studies have been carried out mainly from the viewpoint of heat transfer and flow velocity,and few studies focused on the convective heat transfer efficiency.The convective heat transfer characteristics of a circular cylinder under the action of electromagnetic force was numerically studied with the finite element method based on the energy equation of convection heat transfer and basic governing equations of electromagnetic fluid control.The results show that the heat transfer power increases with the increasing of the electromagnetic force when 0<N≤0.8,where N is an action parameter.When 0.8<N≤1.8,the heat transfer power decreases with the increasing of the electromagnetic force.When N＞1.8,the heat transfer power increases with the increasing of the electromagnetic force.By analyzing the flow of the fluid,it's found that the variation of the convective heat transfer power is due to the continuous sinking of the separation point.As the electromagnetic force gradually increases and the fluid velocity around the cylinder increases,the vortex street will gradually be inhibited and the separation point will continue to sink.