The impact of the polarization dismatch between control light and signal light on the nonlin- ear optical loop mirror(NOLM)with two couplers was analysed by using split-step Fourier method (SSFM)that can solve the coupled nonlinear Schr6dinger equation(CNLSE)considering the polariza- tion effect.The simulations show that the waveform distortion,the time jitter and the intensity fluc- tuation of the output signal are induced by the polarization dismatch.And the time jitter and the inten- sity fluctuation are aggravated with the increase of the working speed.