The invention discloses a dysprosium monomer magnet with the dual functions of ferromagnetic and ferroelectric, the chemical formula of which is represented as [Dy3(L)2(NO3)4].EtOH, wherein L is N, N, N', N'-tetrahydroxyethyl-ethylene diamine; and EtOH is ethanol. Three Dy atoms of different coordination environments exist in the dysprosium monomer magnet and form an unclosed triangle three-core Dy structure; a preparation method of the dysprosium monomer magnet is as follows: dysprosium nitrate hexahydrate is used as metal salt; L is used as a ligand, and LiOH is used as an alkaline substance to adjust the pH value to 7; and a mixed liquid is prepared by stirring, baking, separating and washing solids. The invention has the advantages that: the dysprosium monomer magnet not only shows rare dual relaxation monomer magnet behaviors, but also shows excellent ferroelectric properties; therefore, the material has high potential using values in solid devices like nanometer devices, low-temperature high-density storage devices, ferroelectric memorizers, infrared detectors, surface acoustic waves, and integrated ferroelectric devices, etc.