Abstract: The paper study the power control of the motion satellite, based on the broadcast delay feture of the motion satellite communication system. A moment-generating-function based approach is used in this paper for analyzing the system performance with imperfect power control. Compared with the previous work,to bring down the error of power control, analyzing the channel model, calculating the offset factor,giving the result of simulation, our whole evaluation procedures are easily formulated and the average error performance in compact forms can be obtained to ease the examination of effects of different system arameters.