An air-cooled large energy narrow pulse width MOPA laser pump by a high power laser diode array (LDA) is developed. The end pump Nd∶YAG crystal and decompress electro-optical Q-switching method are used in the oscillation stage and at the repetition rate of 25 Hz, 78 mJ single pulse energy, pulse width of 5.59 ns and beam quality factor of M²≈6.7 are obtained. The laser amplifying stage adopts side-pump zig-zag slab Nd∶YAG crystal dual-pass amplification mode, and at the repetition frequency of 25 Hz, a single-pulse energy of 439 mJ with a pulse width of 6.29 ns and a peak power of 70.46 MW was obtained, with an optical conversion efficiency of 15.25%, a beam quality factor of M²≈8.8, and a continuous operation of 3 min with an energy instability of less than 5%. When output in burst mode, the repetition rate is 1 Hz, the number of sub-pulses is 10, the interval of pulses of 2 ms, and the pulse envelope energy of 4.37 J. The laser adopts semiconductor thermoelectric refrigeration (TEC) combined with forced air cool as the heat dissipation mode, eliminating the bulky water cooling system and realizing the miniaturization of high peak power Nd∶YAG lasers and no water cooling.