Abstract: All-optical switching based on nonlinear polarization rotation(NPR) effect in semiconductor optical amplifier(SOA) has a fast speed and is also integrated together easily. The optical switching operation can be achieved by the different currents of injecting SOA. The performance of this optical switching is also influenced by the input power and the electric current. In this paper, theoretical analysis of the relationship between NPR effect and control current was proposed. Experiments results of polarization rotation with different optical power injected were provided. The optical splitting ratio and extinction ratio were important factors of optical switching. The results show that with the increase of input power the splitting ratio was also increased which could effectively improve the capability of optical switching. In the experiments, an optical switching with high optical splitting ratio and extinction ratio of 30 dB is realized when optical power injected is 5 dBm.