One-dimensional dynamic semiconductor model was presented. The model has been used to investigate the influence of different laser power density on the laser ablation and the expansion of plume. The laser ablation is greatly influenced by laser power density. The more intensive the laser power density is, the higher surface temperature it would have. In this case, the depth of evaporation, the temperature of vapor, and the expansion velocity and spatial scale of ablated plume will also increase with the rising of laser power density. Meanwhile the more intensive the laser power density is, the earlier the plasma shielding would appear. For the given conditions, the threshold of plasma shielding value is between 1×108 W/cm2 and 1.5×108 W/cm2.