The fluorescence of two Tb 3+ aminopolyphosphonic (L 1) acid Phen triple complex (L 1=ethylenediaminetetrakis (methylphosphonic) (EDTP) and ethylaminobis (methylphosphonic) (EDP)) in solution was reported.It was found that fluorescence of Tb L 1 Phen solution apparently increased as compared with that of Tb Phen complex,indicating that Tb L 1 Phen triple complex was formed.The fluorescence was strongest at pH 7.0.Fluorescence for both L 1=EDTP and EDP increase with addition of L 1 and Phen,but excess of ligands did not affect the fluorescence,thus indicating there is cooperation effect between L 1 and Phen.The change of the fluorescence among different complex was also explained according to the enhancing or quenching effect of ligands.