This paper studies the performance of a diagonal channel Magnetohydrodynamic (MHD) power generation. This system includes a diagonal conducting wall MHD generator. As a model of channel, we use a scramjet-driven MHD generator where the MHD generator is directly integrated into the propulsion system. The channel specification is 59.28 cm in length. The working plasma for the power system is generated from freestream air and conventional scramjet fuels combustor. As a result, we present the flow velocity, current density distribution and power generated. And in this case, it can be found that the combustion efficiency of 95% has better power generation than 85 and 75% combustion efficiencies.