The efficiency of power synthesis will be reduced due to the difference of gain and phase consistency between solid-state power source modules. In this paper, a model of the impact of gain and phase consistency on the efficiency of power synthesis is established. Base on this model, the synthesis efficiency distribution under different gain and phase distributions is calculated with the MATLAB software. The simulation results provide the specific phase and gain index for the transmitter design and a strong theoretical basis for the evaluation and acceptance of the transmitter.