The effect of expansion moving and impulse coupling in pulse laser and aluminum target debris were investigated, the spatial and temporal distribution rules of velocity and pressure in aluminum target debris and plasma were analyzed by numerical simulation, and the quantitative relation of impulse coupling coefficient and laser power densities was also discussed. Further, a dynamic deorbit model of ground-based pulse laser irradiating small scale space debris in low earth orbit (LEO) was established, and the effects of orbital eccentricity and perigee altitude with different number of pulses were simulated in the process of removing small scale space debris in LEO. The results indicate that the small scale space debris in LEO could be deorbited availably by optimal impulse coupling coefficient when the number of pulses was 180 times, orbital eccentricity was 0.071 based on the condition of this paper. The prospective achievements can provide technical guidance for the application of high power laser removing space debris in LEO.