This paper presents the possibility to generate the alternating current (AC) electrical power by using a linear MHD generator.The singlesided exciting winding of the generator is considered. Its structure consists of a channel, an insulator and stators. The channel type is a flat rectangular and the liquid flows along the channel as a conductor. The channel wall acted as an insulatorseparates the metal fluid and stator coil. The top stator winding of the generator is connected to polyphase systems. Under this condition, it can produce a magnetic field by means of time harmonics function in the same direction of the metal fluid. Energy in the channel is extracted by inductive coils at the bottom stator. An interaction between traveling wave and metal fluid isexplained by finite element technique. The distributions of magnetic vector potential and magnetic field throughout channel are evidently shown in xyplane.Power flow in an AC MHD generator is reported with magnetic Reynolds number and slip value.The optimized value of active power is suggested by small slip value as s < 0 and small magnetic Reynolds number.