Abstract: In order to optimize the signal reception performance under the saturation condition of the satellite transponder channel, the generation of the intermodulation signal in the saturated state of the transparent transponder is analyzed, and the influence of the intermodulation signal on the deterioration of the channel carrier-to-noise ratio (CNR) is weakened. This paper studies the problem by establishing the channel model, calculating the channel parameters, optimizing the analysis and simulation. The direct influence of the transponder gain adjustment on the CNR of the receiver and the indirect influence of the intermodulation signal on the CNR of the receiver are respectively studied, and did the theoretical calculation and simulation analysis. The results show that under saturation conditions, the transponder gain back off can improve the CNR loss. When the transmit power of the interfering signal is 45 dBW, the minimum CNR loss of −1.55 dB can be achieved by the back-off of the transponder −1 dB. As the interference increases, the optimal gain back off value will gradually increase, and the minimum CNR loss will also increase. The research results in this paper can be applied to satellite transponder channels to provide guidance for the optimization of transponder gain adjustment under saturation conditions.