This paper investigated the impact of Rayleigh backscattering (RB) noise in the proposed wavelengthdivision-multiplexed (WDM) single-fiber loopback access network. RB noise’s impacts on the downstream and upstream service were discussed in details. It was found that the receiver sensitivity was less sensitive when the seeding-light power was below - 12.6 dBm. And for the uplink RB noise, a higher reflective semiconductor optical amplifier (RSOA)’s bias current results in lower receiver sensitivity.