Abstract: The electromagnetic body forces, which is caused by the electromagnetic field and is localized on the circular cylinder surface, have been used to modify the boundary layer of flow and control the flow field of the circular-cylinder flow in electrolyte solution. The key parameters of control experiments have been confirmed by theoretical analysis and numerical simulation. The electrodes and the magnetic poles are flush mounted on the cylinder surface side by side in the sequence of magnet N-pole, positive(negative)electrode, magnet S-pole, negative (positive)electrode, and so on. The cylinder covered with electro-magnetic actuator is immerged in the flowing electrolyte solution. By using the electro-magnetic shielding and the time-region control methods, the separation points of the circular-cylinder flow are moving between the front stagnation point and the back stagnation point as the varieties of the space-time distribution parameters of the electromagnetic forces, and it brings different control effects. The electromagnetic force modified on the boundary layer is convenient in controlling the flow field structure of the circular-cylinder flow and the cylinder wake, and it achieves the obvious effects of the vortex suppression and the vortex acceleration. The method provides preferable effects of vibration suppression, drag reduction, and damping control.