A new ternary terbium complex with 2,6-pyridinedicarboxylic acid (DPA) and 2,2'-bipyridyl (bipy) as ligand was synthesized and characterized by EDTA titration, elemental analysis and FTIR. The complex showed strong and stable electrochemiluminescence (ECL) property in NaBO4-NaOH buffer solution (pH = 10.0) with the coreactant of potassium peroxydisulfate. The possible mechanism for the ECL behavior of terbium complex was discussed. Base on the ECL of the complex, a simple and ultrasensitive detection method for norfloxacin (NFX) was thus established. Under the optimized conditions, the enhanced ECL intensity versus the concentration of norfloxacin was in a good linear relationship over a concentration range from 1.0 x 10(-9) to 4.0 x 10(-7) mol/L. The detection limit was found to be 6.9 x 10(-10) molt L. The mechanism of ECL enhancement of NFX was also studied. The results obtained by the proposed ECL system, in terms of sensitivity, were much better than those obtained previously reported methods. In addition, the method was applied successfully to determine the total residuals of the norfloxacin in urine samples, the recoveries obtained were from 98.0% to 101.0%. (C) 2014 Elsevier B.V. All rights reserved.