Dual-wavelength and multi-wavelength lasers have received considerable attention recently and have been used extensively in interference rain bow holograph, fine laser spectrum, differential absorption radar, multi-photon step ionization of atom and molecular, nonlinear frequency conversion and laser medicine fields. By using the Nd:YAG crystal while adopting the methods of laser diode (LD) side-pumped, electro-optical Q-switched, multistage amplifier and the technology of polarization controlled by electricity, the switchable output of dual-wavelength of 1 064 nm and 532 nm is acquired. The single pulse energy is 750 mJ at 1 064 nm, when 1 064 nm laser with 230 mJ single pulse energy is input, single pulse energy is 106 mJ at 532 nm, corresponding to the repetition frequency of 100 Hz and the conversion efficiency of 46%. The above laser can be applied to the fields of airborne, spaceborne, shipborne laser ranging and illumination, radar and the laser environmental monitoring as its feature of stable orientation.