An optical preamplifier is utilized to improve the signal-to-noise and distortion ratio RSNDR of inter-satellite microwave photonics links considering the large signal losses in distant propagation and serious deterioration caused by inter-modulation distortion. An optically preamplified inter-satellite microwave photonics links model with two radio-frequency (RF) signals input is established and an analytical expression of RSNDR is derived. The direct current (DC) bias phase shift of modulator can be optimized so as to maximize the RSNDR given the desired input RF signal power, and the effects of the optical preamplifier parameters on the optimum DC bias phase shift and RSNDR are also examined. Simulation results show that the most limitative factors degrading the RSNDR are changed, and the fundamental power is seen to increase more compared with the power of third-order intermodulation (IM3) plus noise due to optical preamplifier. Thus, RSNDR can be improved with respect to the case of non-optical preamplifier. For the preamplifier gain of 20 dB and noise figure of 3 dB, an improvement of about 24 dB in optimum RSNDR is accessible. The optimum DC bias phase shift is found to be insensitive to the preamplifier gain and noise figure while the optimum RSNDR is sensitive to the preamplifier gain and noise figure.