The fluorescent responses of 3,3'-di(trifluoroacetyl)-1,1'-bi-2-naphthol toward a variety of amines have been studied. It was found that the aliphatic primary 1,2- and 1,5-diamines can greatly enhance the fluorescence of this compound, but under the same conditions, primary, secondary, and tertiary monoamines cannot turn on the fluorescence of this compound. In addition, this compound was shown to be an enantioselective and diastereoselective fluorescent sensor for chiral diamines. UV absorption and NMR spectroscopic methods have been used to study the interaction of the sensor with amines. These studies have demonstrated that the intramolecular OH···O═C hydrogen bonding of the sensor is important for both the reactivity of its trifluoroacetyl group with the amines and its fluorescent responses. The interaction of both of the two amine groups of a diamine molecule with the sensor is essential for the observed fluorescent sensitivity and selectivity.