The dynamic model of the semiconductor fiber ring laser is developed and investigated numerically. A semiconductor optical amplifier (SOA) model is employed in which the self birefringence of SOA due to stress is taken into account. The integral action of the birefringence of the fiber and the PC is represented with a Jones matrix of linear retarder. The dynamics model was simulated with Matlab software. The ranges of the linear retardation and the azimuth of the fast axis of the linear retarder are founded, in which the ring laser can generate polarization chaos. The effect of injected current of the SOA on the generation of polarization chaos in the ring laser is explored. The simulation results of the relationships between optical powers, degrees of polarization (DOP) of fiber ring laser and currents of the SOA are consistent with the experimental results reported earlier. A conclusion is drawn that the bigger the injected current is, and the more adjacent to zero the linear retardation and the azimuth of the fast axis of the linear retarder are, the easier the semiconductor fiber ring laser generates polarization chaos with high frequency.