On the basis of analysis on interaction between processing materials and three types of lasers, i. e., free-running, CW-acoustic-optical Q-switched and PW-acoustic-optical Q-switched Nd:YAG laser, the experiments on laser drilling with these lasers were carried out. It was shown from analysis and experiments, PW-acoustic-optical Q-switched Nd:YAG laser can be used in drilling to attain high quality drilling holes with less recast layer and free cracks.