Amino acids are the primary units of proteins and play an important role in human life. The coordinate of L-tyrosine with rare-earth element Eu(3+) was investigated in solution by ultraviolet and was proved the molar ratio is 1:2. Then the solid complex was prepared by coprecipitation method. The complex was characterized by several analytical techniques, including Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electron Microscopy, 1H-NMR and 13C-NMR. Based on these data, we found that pentatomic ring was formed by binding with N atom in group of amino (-NH(2)) and O atom in group of carboxyl (-COOH).