The relative intensity noise (RIN) of lasers will change to noise power in microwave photonic links, which limits the dynamic range. Theoretical models of spurious free dynamic range (SFDR) in basic configurations of non-coherent and coherent microwave photonic links were established, and the impact of RIN on the two kinds of links was analyzed and comparedby simulation.When the performance of optical devices was low, non-coherent microwave photonic link would exhibit lager SFDR; as the performance of optical devices increases, the SFDR of coherent microwave photonic link would exceed that of non-coherent microwave photonic link. Moreover, under the conditions of typical optical devices nowadays, the theoretical SFDR of both two kinds of links can reach 120dB·Hz2/3.