This paper reports a microwave frequency dissemination experiment over a 56 km-long-fiber link in the laboratory， exhibiting frequency instabilities of 1.8×10^-15/s and 4×10^-18/10⁴s. The phase perturbation accumulated along the fiber link is detected by comparing the round-trip signal with the reference signal. By controlling the phase of the transmitted signal in real time， the phase perturbation along the fiber link is compensated. Different modulation frequencies are used to avoid stray reflection effect. To improve the phase noise of the detection signal， we also implemented dispersion compensation.