When using YAG laser emit strong laser pulses to bombardment solid POM, in the areas of interaction will produce a plume. A shadowgraph photography technique was employed for visualizing temporal evolution of plume. The experiment results show that in the plume flow field, multi-density discontinuities were observed. The plume has a high speed towards laser source, and plume uneven expansion makes the shape and position of discontinuities change. Plume velocity affect the propulsive efficiency, enhance the pulse laser energy can speed up the plume, energy increase to a certain degree of plume speed will reach a steady-state value.