Erbium-doped fiber amplifier (EDFA) is widely used in the optical communication system, and it is usually used as a linear amplifier in most scenarios. However, in analog photonic links, we observe the nonlinear spurs caused by EDFA. In the analog photonic link, the dynamic range is one of the most important characteristics while the nonlinear spurs set the upper limit of input signal power. We study the nonlinearity caused by EDFA in analog photonic links when the input power of EDFA fluctuates at a low frequency. We have theoretically and experimentally studied the characteristics of the nonlinear spurs caused by EDFA.