A nonlinear dynamic model of fiber optical current transformer (FOCT) was deduced on the basis of physical model with reasonable equivalent approximate. The nonlinear model was simplified to linear discrete model, and simulation analysis was carried out. Based on the characteristic of noise, a random noise model was established. Then, the random noise was simulated in different stochastic processes. Simulation results show that the model is reasonable, and the random noise generated by simulation can reflect the statistical characteristics of noise in optical fiber current transfer.