A scenario of external magnetohydrodynamic (MHD) generator on board blunt-cone based reentry vehicles was proposed, and numerical parametric studies by employing an MHD model based on the low magnetic Reynolds number approximation were performed. Following the numerical results, the physical features of the external MHD generator were drawn. One may conclude that the power output of the external MHD generator is capable of providing energy output up to 1.28 MW under the typical reentry condition (flight height 46��km,velocity 7��km/s). Under the MHD power extracting operation, the drag coefficient of the reentry vehicle is raised by 13.7%, whereas the total wall heat flux varies mildly. However, the distribution of heat flux density in the MHD power extraction zone and downstream differs distinctly from that in the original N-S flow. The peak heat flux densities in the area occur at the tips of the electrodes.