Abstract: In order to construct a micro acousto-optic Q-switched Nd:YVO₄ laser with narrow pulse width, based on active Q-switched rate equation, the influence of pump speed, repetition rate and output mirror transmittance on pulse width was analyzed.The laser was designed with the structure of simple flat-flat cavity. High gain Nd:YVO₄ laser crystal was end pumped by LD. A micro acousto-optic Q-switched was inserted in the resonant cavity, with action length of 7mm, cavity length of 13mm, and output mirror transmittance of 70%.The results show that when the pump power is 4.21W and repetition rate is 20kHz, the output of 1064nm laser was obtained with single pulse energy of 20μJ, pulse width of 1.65ns and peak power of 12kW. It is feasible to use micro acousto-optic Q-switched to construct short cavity and obtain narrow pulse width output. The device can also be used as the seed source of high-power lasers.