The invention discloses a single-core 
dysprosium complex based on 2-methyl-5,7-dibromo-8-hydroxyquinoline serving as a ligand as well as a preparation method and application of the single-core 
dysprosium complex. The complex has a 
chemical formula of [Dy(L)3(H2O)], wherein L is 2-methyl-5,7-dibromo-8-hydroxyquinoline with 
hydrogen atoms of hydroxyl being removed and is charged with a unit of 
negative charge. The complex belongs to a monoclinic 
system with C2 / c space groups. The preparation method of the complex disclosed by the invention comprises the following steps: taking Dy(NO3)3.6H2O and 2-methyl-5,7-dibromo-8-hydroxyquinoline, dissolving with a mixed 
solvent, regulating the pH value of the obtained solution to be 6.5-7.8, reacting the obtained 
mixed solution under heating conditions, thereby obtaining the product, wherein the mixed 
solvent refers to a combination of 
chloroform or 
deuterated chloroform and water. The complex provided by the invention is simple in preparation method, low in cost and high in 
repeatability, presents a slow relaxation magnetic behavior at low temperature and can be used for preparing magnetic materials.