A novel quinazolinone derivative ethyl 2-(2-methyl-4-oxo-1,2,3,4-tetrahydroquinazolin-2-yl) acetate (EMOTA) was synthesized and characterized by HRMS, ¹H NMR, ¹³C NMR spectroscopy and X-ray crystallography, and the ion recognition performance of the compound was studied by fluorescence analysis measurements. The results showed that probe EMOTA has a rapid fluorescence response, good selectivity and sensitivity to Fe³⁺. When the concentration of Fe³⁺ was in the range of 0~10.0 × 10^-5 mol/L, the fluorescence quenching could be affected by the probe, and the detection limit was 1.65 × 10^-6 mol/L. In addition, the identification and detection of Fe³⁺ in water samples were studied, and the results showed that probe EMOTA has high efficiency, significant sensitivity and high selectivity on the recognition and detection of Fe³⁺ in water samples, which indicates probe EMOTA has a practical application prospect.