Abstract: Using the high-power laser diode array (LDA) end-pumped Nd:YAG laser bar method, combined with the design of the convex-concave unstable cavity, the average energy of the small beam divergence laser output was achieved about 83 mJ under 20 Hz operating conditions. Then taking the laser as the oscillation source, the same method of the LDA end-pumped Nd:YAG laser rod was used for energy amplification to form an LDA end-pumped master oscillator-power amplification (MOPA) laser, which finally obtained the pulsed laser output with a repetitive frequency of 20 Hz, an average energy of >200 mJ, a divergence angle < 2.1 mrad and an energy fluctuation < ±2.5%. The laser has a optical-to-optical conversion efficiency of about 14.6%, a volume of 175×91×49 mm³, a mass of < 1 kg, and a divergence angle of < 0.3 mrad after transmitted through an 8^× transmission antenna.