The primary technical issues of high peak power and large energy Nd:YAG solid state laser are researched. A pair of Nd:YAG rods are used to realize the above laser, and some techniques are discussed in detail. Characteristics of the Q-switch of pulse drives with KD*P crystals and the double-channel 6-step traveling-wave power amplifier are presented, inspectively. The 45° beam polarized combination of two Nd:YAG lasers using polarization coatings are completed. The experimental results are presented: at 20.0 Hz, output energy exceeding 8.5 J per pulse, pulse width 13.9 ns, beam quality M2≤3.99 and energy unstabllity degree less than 0.5%.