For the laser peening technology which is a recently-developed surface treatment method designed to improve the fatigue life of mechanical parts, using a oscillation eight-stage amplified system structure and the modular design method, high-energy, short-pulse and high-frequency Nd:YAG solid-state lasers are developed. Design scheme of the laser and the characteristics of laser beam transmission are presented and discussed. At ambient temperature which changes less than 2 ℃ and after 20 min of warm-up, the technical parameters such as the maximum single pulse energy of 25 J, energy instability less than 3%, pulse width which can be continuously adjustable between 16 ns and 20 ns, pulse width instability less than ±1 ns, beam divergence less than 2.5 mrad, and the maximum single frequency of 5 Hz are achieved. To further verify the performance of the lasers, a TC4 titanium alloy work-piece is tested with the Nd:YAG lasers. The tested results show that the compressive residual stress is greatly improved and the performance of the lasers is excellent.