The invention provides a triazinyl tricarboxylic acid heavy rare earth complex. The specific chemical formula is [Ln2(TCT)2(H2O)6].6H2O, wherein Ln is selected from Tb or Dy or Ho or Er or Tm or Yb or Lu, TCT is 2,4,6-tri(carboxymethyl sulfydryl)-1,3,5-triazine negative ion, and meanwhile the invention provides a preparing method and a characterization method of the triazinyl tricarboxylic acid heavy rare earth complex. Synthesis raw materials are easy to obtain, the synthesis method is simple, a reaction does not be carried out under the high-temperature high-pressure hydrothermal or solvothermal condition, the cost is low, and the yield is high; the synthesized triazinyl tricarboxylic acid heavy rare earth complex is poor in water solubility, and is also difficultly dissolved in a common organic solvent, and secondary pollution to the environment is prevented; the prepared triazinyl tricarboxylic acid heavy rare earth complex shows the ligand-sensitized rare-earth-ion-lighting and the field-induced slow magnetic relaxation behavior, and can serve as applications of light and magnetism function materials.