The synthesis of a simple fluorescent naphthalimide-based receptor N -allyl-4-iminodi( N -butylacetamide)-1,8-naphthalimide 3 was carried out as a selective picrate (Pic – ) anion probe, and the detecting behavior of this probe was studied by fluorescence spectroscopy. In DMF solution, the interaction of compound 3 with different anions, including Pic – , F – , Cl – , Br – , I – , OH – , Ac – , NO 3 – , ClO 4 – , SCN – , SO 3 2– , SO 4 2– , H 2 PO 4 – , and HPO 4 2– , revealed significant fluorescence quenching only with the Pic – anion. By adding the picrate anions, green-yellow fluorescence emission quenches, which is easily observed by naked eyes under a 365 nm UV light irradiation. This phenomenon is essential for producing a highly selective and sensitive fluorescent probe for picrate anions. The probe can be applied to the quantification of Pic – with a linear range covering from 4.97 × 10 –6 to 6.82 × 10 –5 m and a detection limit of 5.8 × 10 –7 m . Most importantly, probe 3 has a high selectivity for picrate over competitive anions and picrate-containing analytes, which meet the selective requirements for practical application. Thus, the present results would be inspiring findings in the future design of reaction-based fluorescent turn-off probes for the environmentally relevant picrate probe.