The distribution of the electromagnetic force around a cylinder covered by electromagnetic actuators was obtained by solving the Maxwell equation system, and such an electromagnetic force was added to the momentum equation of the flow governing equation system. The detached eddy simulation (DES) method was adopted to simulate and analyze the flow characteristics around a circular cylinder and its lift/drag characteristics in a weakly conductive fluid at Reynolds number Re=3 900. Results show that the electromagnetic force can increase the fluid kinetic energy near the cylinder wall, delay flow separation and weaken the flow threedimensional effect, as well as the jet phenomenon produces after the electromagnetic force parameter reaches some certain critical value. Moreover, the total and pressure difference drags decrease with the increase of the electromagnetic force parameter; however the friction increases, and the electromagnetic force can significantly reduce the lift fluctuation amplitudes.