Abstract: According to the application requirement of high-quality drilling, the authors design a novel high peak-power acousto-optical Q-switched pulse Nd:YAG laser. AOM is used in cavity to modulate pulse Nd:YAG laser for improving peak-power of laser pulse. The set-up and Q-switching pulse sequence of laser are given. The Q-switch pulse train of laser with the duration of 200 ns during each flash-lamp pulse is obtained. The repetition rate of the train is (5-50) kHz, the pulse energy is 30~ 80 mJ, and the peak power is more than 400 kW with an output beam parameter product of about 3 mm mrad. The laser has been used to drill the Ni-alloy of 1.5 mm thick, resulting in thinner recast layer and less micro cracks.