highly selective fluorescence "turn-on" response. The competitive assay showed that the presence of other analogues (cyanuric acid, cyanuric chloride, trichloroisocyanuric acid and acetoguanamine) rarely affected the turn-on fluorescence intensity in probing melamine. The obtained results displayed a linear correlation beteewn melamine concentration and fluorescence intensity. The linear equation was y = 38.68x + 568.32 (R 2 = 0.9972) with melamine concentration ranged from 5-100 µmol/L. When melamine concentration reaches 100 µmol/L, the fluorescence intensity becomes the maximum. The formed Eu III-dtpa-bis(melamine)-melamine complex was extremly stable with the stability constant (k) of 9.90 × 10 6 and the complexation ratio was 1:1. The detection limit (LOD) was 0.3743 µmol/L. The recoveries ranged from 99.80 to 100.50 %, when melamine was detected in some milk products. It can be confirmed that Eu III-dtpa-bis(melamine) shows high selectivity, sensitivity, targeting and recognition ability in melamine detection.