Abstract: The mechanism of nonlinear optical loop mirror(NOLM) based on all-optical demultiplexing of hyperbolic secant pulse for both signal and clock was theoretically analyzed.The expression of minimum initial peak power of clock pulses,with which the switching efficiency of pulses peak up to 100% can be obtained,was demonstrated.The influence of walk-off time,initial time delay and initial peak power of clock pulses on the shape of output signal were numerically analyzed.The results show that the walk-off between clock pulses and signal pulses plays an important role in all-optical demultiplexing based on NOLM,the lager the walk-off time is,the smaller the peak power of converted signal is,and the more asymmetric the waveform is.Also,it's found that proper initial peak power of clock pulses can compensate the walk-off induced degradation,and initial time delay between clock pulses and signal pulses can balance the waveform asymmetric of converted signal induced by walk-off.