Abstract: Solution－phase synthesis can synthesize nanometer－sized materials with narrow size distributions and functional surfaces, enabling both the formation of order arrays and the controlled tethering of nanometer－sized materials to solid substrates by chemical reaction in homogeneous solution which leads to homogeneous or heterogeneous nucleation and diffusion growth. The two－phase reduction method, reverse micelle method, and high－temperature solution－phase synthesis are described as well as the influence factor of high－temperature solution－phase in the preparation of monodisperse metal nanoparticles. Recent progress in the synthesis of metal nanoparticles, especially magnetic nanoparticles, and potential applications are discussed.