Abstract: A theoretical investigation of the pulse trapping has been analyzed and different incidence conditions have been discussed when the two pulses are polarized along the fast axis and slow axis, respectively.The numerical simulation results show that the optimal pulse trapping effect can be obtained by choosing the appropriate time domain center delay.The red shift of the pump pulse and the blue shift of the signal pulse are larger when the peak power of the pump pulse increases.But it is difficult to achieve pulse trapping when the power increases to a certain extent.With the increase of pump pulse half-width,the signal pulse output spectrum intensity becomes smaller and the pulse trapping becomes worse.If the change of wavelength leads to a large group velocity difference,the pulse trapping effect decreases,or even disappears.