A highly stable acousto-optical Q-switched 532 nm Nd∶YAG laser based on a type Ⅱ LiB3O5(LBO) crystal intracavity frequency-doubling is demonstrated. Average output power of 126 W of green laser is obtained at a repetition rate of 12 kHz for acousto-optical Q-switched laser. Test results show that the pulse width is 52 ns, which corresponds to a pulse energy of 10.5 mJ and a peak power of 205.9 kW. The diode-to-green optical conversion efficiency from 808 nm to 532 nm is 9.19%. The LBO crystal's temperature is precisely controlled by a temperature control furnace with the precision of ±0.1 ℃, which directly contributes to the high efficiency high-stability second harmonic generation. The output power of the green laser is very stable. The root mean square instability of green laser at 126 W is calculated to be ±0.628% in 3 h of continuous work.