Abstract: The use of magnetic control method could improve the scramjet propulsion performance. The Maxwell equations and N-S equations were combined and these equations were simplified. The flow field numerical simulation model of distribution was established to calculate the MHD scramjet magnetic inlet flow field. The flow field characteristic, electric potential, current and power extraction were studied under certain conditions. MHD generator could reduce the Mach number flow speed and total enthalpy at the exit of the pipe. However, the temperature would increase at the exit of the pipe. The electric potential remained constant at the electrode and the electric potential was higher on the insulation wall and the electric field at the electrode endpoint changed periodically. The current along y direction near the plate electrode was very high and almost zero on the insulation board. The current mainly flowed from the positive electrode to the negative electrode and slightly decreased along the x direction. The maximum current along y direction appeared on the insulation wall and the current along z direction was almost zero on the insulation wall. The z direction current appears at the corner of the pipe and the z direction current on the insulation wall was almost zero. The normal component of the current on the insulation wall was almost zero.