Abstract: Aniline and benzylamine are intermediates of chemical industry and precursor chemicals, respectively. The rapid on-site detection of them is of great significance in environmental detection and cracking down on precursor chemicals. We designed and synthesized a fluorescent probe with benzothiadiazole as the skeleton and aldehyde group as the active unit. The probe film showed fluorescence quenching for aniline vapor at room temperature, while fluorescence enhancement for benzylamine vapor. In air, the material has good light stability, and there is no photobleaching phenomenon within 300 seconds. After contact with aniline gas, it completely reacted within 300 s, with fluorescence quenching of 55% and detection limit of 5.6 ppm. After contact with benzylamine gas, the fluorescence increased by 272% and the detection limit reached 0.63 ppm. For the first time, the fluorescence probe realized the high selectivity recognition of aniline and benzylamine by fluorescence quenching and enhancement, and other common organic amines and solvents had little influence on the detection. NMR and MS analysis showed that aldehyde group of the probe reacted with aniline and benzylamine respectively at room temperature at solid-gas interface to generate corresponding Schiff bases. Quantification shows that the different charge transfer and spatial structure of Schiff base lead to different fluorescence signal changes. The probe is expected to be applied in the detection of aniline environmental pollutants and benzylamine raw materials in drug-making dens, providing technical support for environmental monitoring and drug control.