In an experiment on the round-trip fiber transfer of joint frequency and time signals based on wavelength-division multiplexing technology, a specific bidirectional erbium-doped fiber amplifier (Bi-EDFA) with low noise and high symmetry simultaneously is designed and applied to compensate for the loss of the link. The Allan deviation (ADEV) deterioration of the 1 GHz frequency signal induced by the Bi-EDFA is only 8×10 15 at 1 s and 9×10 18 at 104 s in the forward direction, and is 1.7×10 14 at 1 s and 1.2×10 17 at 104 s in the backward direction. The degraded time deviation (TDEV) caused by the asymmetry of the Bi-EDFA is only 0.8 ps at an average time of 103 s. With the proposed Bi-EDFA, in the field experiment on the 110 km fiber transfer of joint frequency and time signals, the ADEV of the 1 GHz frequency signal is 7.3×10 14 at 1 s and 2.5×10 17 at 104 s. The TDEV of the 1 pulse per second time signal is 6.8 ps with an average time of 1