Based on the theoretical analysis of cascaded optical fiber time and frequency dissemination system, the general formula of total time jitter is calculated. A two-stages optical fiber link for ultra-stable frequency dissemination with a total fiber length of 2×50 km is demonstrated. Then the phase error voltage and time jitter of single-stage and two-stage systems in closed-loop is measured. After comparing experimental results and theoretical calculation, the main sources of experimental error is analyzed. Analyze the impact of phase noise on signal to noise ratio (SNR), which the phase noise is caused by the amplified spontaneous emission (ASE) of the erbium-doped fiber amplifier (EDFA). The stability of transfer system is gotten due to the decline of signal to noise ratio (SNR).