N-(2-(2-(2-Hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)furan-2-carboxamide (1) that can selectively recognize Fe³⁺ and $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$ was synthesized, which was the first small molecule probe based on naphthalimide to detect $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$. The pH titration showed that the spectral red shift caused by the enhancement of intramolecular charge transfer (ICT) effect was as a result of formation of amide anion. Besides, the selectivity, concentration titration, time dependence, quenching constant, detection limit and recognition mechanism of probe 1 to Fe³⁺ and $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$ were also studied in CH₃CN/N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer solution. The results showed that Fe³⁺ and $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$ could rapidly quenched the fluorescence of probe 1 through the inner filter effect. The quenching effects remained constant after 30 s, and the quenching constants were 6.14×10³ and 6.55×10³ L•mol^–1, respectively. The detection limits of probe 1 for Fe³⁺ and $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$ were 1.62 and 1.56 μmol/L, respectively. The determination of Fe³⁺ and $\text{C}{{\text{r}}_{2}}\text{O}_{7}^{2-}$ in water samples made it clear that probe 1 could be used as a potential detection tool in practical application.