Abstract: Aiming at the applying demand of airborne laser ranging and laser indication, a compact and reliable electro-optical Q-switched laser was designed.Based on the rate equation with Q-switched, the relationship that the laser output energy increased with the increasing optimization parameter z and the pulse width decreases with increasing z was analyzed. The Nd:YAG laser crystal of ø6.5mm×56 mm, LD side pump, u model of folded cavity which applied cube-corner prism for folding the light, was used as the resonator cavity. The anti-misalignment ability of resonator cavity can be improved under the premise of gain satisfaction. Under the condition of 1.2 J implanted electrical pulse, the energy output of laser single pulse is 108 mJ, the pulse width is 11.8 ns, the energy instability is less than 0.8% and the light efficiency is 18%, which can be stably operated for a long time.