A detached eddy simulation method with the turbulent separation is presented to simulate and analyze the characteristics for the flow around a circular cylinder with a turbulent boundary layer separation and its lift/drag coefficients in a weakly conductive fluid at a high subcritical Reynolds number 1.4×105 under an electromagnetic force. The results show that the electromagnetic force can increase the fluid kinetic energy near the turbulent boundary layer, delay the turbulent boundary layer separation of the flow around the circular cylinder, and weaken the intensity of the large-scale eddy in the turbulent flow around the circular cylinder in the streamwise and spanwise directions, reduce the time-average drag, and inhibit the lift fluctuation amplitude on the circular cylinder. Moreover, after the electromagnetic force parameter reaches a certain critical value, the turbulent boundary layer separation disappears and the jet phenomenon appears in the wake of the circular cylinder, so that the electromagnetic force produces the thrust action on the circular cylinder and the negative drag occurs, and the lift fluctuation amplitude declines to almost zero and the lift phenomenon on the circular cylinder disappears.