The experiment results of high peak power lamp-pumped pulsed Nd∶YAG laser adopting symmetrical parallel plane cavity are reported. Base on the rate equation, the expression of single pulse energy of pulsed Nd∶YAG solid-state laser is derived with the simulated optimum transmissivity and maximum output energy. The optimal parameters are obtained by the experiments, and a high peak power lamp-pumped pulsed Nd∶YAG laser is developed with the results of theory simulating and optimal experiments being consistent with each other. When the laser works under 800 V voltage, 2 ms pulse width, it outputs laser with energy of 60 J, high peak power of 30 kW with beam quality M2=5.9, and the total electro-optic efficiency of 3.3%. When it works under 800 V voltage, 1.5 ms pulse width, the maximum output average power is 405 W. The 6 mm mild steel and 4 mm stainless steel were cut by the laser with the 2 ms pulse width, 6 Hz frequency and 30 kW peak power. The cutting speed for 4 mm stainless and 6 mm mild steel is 1 mm/s and 1.5～2 mm/s, respectively.