Abstract: In the experiments, it was found that the momentum coupling coefficient of multi-pulse propulsion was lower than that of the single pulse case for the air-breathing mode. To learn the mechanism of this phenomenon, the multi-pulse simulation of the parabolic flyer taken as a moving object was carried out using the dynamic mesh method of the commercial code FLUENT, the error that made by neglecting the after-effect of the flow field was taken into account. The results show that the average momentum coupling coefficient decreases with the number of the laser pulses, but the trend of slewdown is obvious. The simulation results agree well with the experimental results, and the after-effect of the flow field induced by the laser pulse can not be neglected.