We analyze the differences of static and dynamic power transfer functions (PTFs) and Q-factor transfer function (QTF) for clock-pumped four-wave mixing (FWM) fiber regenerators with the optical signal degraded by spontaneous emission noise. The influence of extinction ratio on the dynamic PTF curve is revealed. The dynamic PTF and QTF characteristics of all-optical regenerator are studied emphatically and the simulation results are in good agreement with the experimental data. It is shown that the input optical power corresponding to the PTF′s output saturation point is larger than that to the QTF′s optimal operating point by 1 dB for the given wavelength configuration and optical fiber parameters. Besides, the point is basically independent of the pump optical power. This conclusion means that the optimal operating point can be derived by measurement of the corresponding dynamic PTF curves.