Abstract: In order to explore a 56J high-energy high-frequency lamp-pumped pulsed Nd:YAG solid-state laser,the main factors affecting the laser output were studied and the relation between the output power and input power and reflectivity was simulated.Then some effective measures were adopted to improve the efficiencies of the laser in experiments.As a result,a high energy Nd:YAG laser was obtained whose pulse width tunable between 0.1ms and 10ms,frequency tunable between 1Hz and 1kHz.When the laser inputs 12kW electrical power,its maximum single pulse energy was up to 56J,maximum average power is up to 500W with its beam parameter product 16.5mm·mrad,total electro-optics efficiency 4.2%,the stability of output power ±2%.The experimental results are corresponding to the theoretical ones.