Iridium (III) complexes have broad application prospects in luminescence detection of analyte due to advantages of large Stokes shift, high quantum yields, long luminescence lifetimes, flexible and adjustable emission spectra, and excellent optical and thermal stability. The novel iridium(III) complex Ir(ppyTPA)₃ was prepared by introducing triphenylamine substituent on 2?phenylpyridine, and the structure, luminescence and electrochemical properties of Ir(ppyTPA)₃ were characterized in detail. Then, the luminescence properties of Ir(ppyTPA)₃ were used to detect five common nitroaromatics and the detection mechanism was studied. The results show that Ir(ppyTPA)₃ has the highest detection efficiency to 3?nitrobenzoic acid with the detection efficiency constant K_SV of 19.78 L/mmol. And the detection limit is as low as 2.89×10^-3 mol/L. Spectral analysis and density functional theory calculations show that the detection mechanism of Ir(ppyTPA)₃ for the five nitroarenes was the charge transfer mechanism.