Abstract: To the output signal-to-noise ratio (SNR) optimization of inter-satellite microwave photonic link, the direct intensity modulation detection inter-satellite microwave photonic link based on dual-electrode Mach-Zehnder modulator (DE-MZM) was modeled, the link performance was improved by optimizing the modulation mode. The link output SNR under single-sideband (SSB), double-sideband (DSB) and push-pull modulation was derived by numerical analysis. The minimum optical amplifier gain of the transmitter and the corresponding optical modulator DC bias point with the given output SNR were obtained by curved surface projection method. The results show that, when the input signal power and the optical emission power remain unchanged, the SNR of DSB modulation is 3 dB higher than SSB modulation, and the optimum SNR is obtained with low DC bias of push-pull modulation. When the input signal power is -20 dBm and the output SNR is 17.3 dB, the needed minimum optical amplifier gain is 43.9 dB, and the corresponding DC bias phase is 0.87 .