The optimizedfluid mechanics model was fabricated to solve the plasma of space debris excited by nanosecond pulse laser. Fluid mechanics model was divided into solution of plasma state equation, energy coupling between laser and space debrisand momentum coupling coefficient. In each module implements, time and space distribution of temperature, velocity, pressure and density of debris plasma were analyzed. Considering the influence of plasma shielding effect to the laser efficiency, innovation was putt forward to achieve the highest efficiency of laser to clean up space debris by the method of absorption mechanism of layer by layer. Influences of pluse width and power density to the momentum coupling coefficient were acheived. Finally, comparing the result to experimental experience data prove the verification of the simulation.