Among parameter system of radar, detection distance and target distinguishable ability are important ones, which are related to compression dynamic range(CDR) and noise figure(NF) of receiving link. Nowadays, applications of radio-over-fiber(ROF) in radar receiving link are moved forward. Besides studying on optical link itself, cooperation analysis on both microwave and optical wave should be given. Therefore, microwave pre-amplifier, ROF link and microwave post-amplifier were coupled together. CDR and NF of receiving link based on ROF were discussed universally. For example, if power spectrum density(PSD) noise of ROF was -164 dBm/Hz and optical gain was -20 dB, the CDR_1dB and NF of receiving link could be 143 dB·Hz and 4.15 dB with pre-amplifier of 41 dB. In this case, detection distance and target distinguishable ability could both match requirements of system. Moreover, parameters of optical devices were also discussed. For ROF based on external modulated optical links, half wave voltage of modulators could be among 2.0 to 5.8 V to balance performances and costs. Therefore, studies from the aspects of system proof that receiving link based on ROF could meet the requirements of radar functions. Design principles for electronical and optical devices were provided in the meantime.