Abstract: To investigate the effect of 157nm laser parameters on the ablation performance, two wide band-gap materials (fused silica and sapphire) were employed in 157nm laser micromachining experiments, and ideal parameter range of laser process was obtained. The ablation rate of sapphire is approximately half of that of fused silica, and the ablated surface of sapphire is much rougher than that of fused silica. With the increase of etching depth, the generated particles are difficult to escape from micro-structures so that the ablation rate decreases. For laser scanning, higher velocity and lower pulse repetition rate are favorable for reducing the surface roughness. Experimental results show that, for the etching of nonmetal materials, the laser fluence should be controlled 2.5 times~4 times of energy threshold of the ablated material, so as to get better etching effect.