Performance improvement of self-induced polarization rotation(SPR) in a semiconductor optical amplifier(SOA) is proposed based on holding beam injection(HBI).Simulation results show that the holding beam injection can dramatically reduce the gain recovery time of TE and TM modes,and speed up the response of SPR in the SOA for the ultra fast signal,though the gains of TE and TM modes are also reduced.As an example of validation,the proposed method is applied in the SPRbased optical power equalization.It is observed that both the distortion of return-to-zero(RZ) signal and the overshoot of non-return-to-zero(NRZ) signal due to the slow gain recovery of the SOA can be significantly suppressed.After the power equalization,the extension ratio(ER) of the output signal can be increased by 8-10 dB for RZ signal and 4-6 dB for NRZ signal respectively,and both signals reach high quality with the Q factor of eye-diagram over 20.