High-quality cubic yttrium iron garnet (YIG) nano powders have been rapidly synthesized by a chemical co-precipitation plus microwave heating method. The average particle size of the synthesized YIG nano powders were about 30 nm. The atoms in the particle were near completely orderly arrangedby microwave activation, resulting in a higher saturation magnetization of 29.7 emu/g and a lowercoercive field of 21 Oe compared with those of conventional heating treatment. This method provides a time-saving and easily controlled route for the synthesis of high-quality YIG nano materialsin large-scale production.