In order to effectively improve the detection of α,β-unsaturated aldehydes in emulsion, this study established an efficient and sensitive detection method using supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). Sample pretreatment conditions and SFC-MS/MS parameters were optimized. It was found that the simultaneous detection of eight α,β-unsaturated aldehydes was achieved within 4 minutes using a mobile phase composed of supercritical CO₂ fluid and acetonitrile under the negative ionization mode. The α,β-unsaturated aldehydes showed good linearity over their respective concentration ranges, limits of quantification (LOQ) lower than 1.8 μg/kg and spiked recoveries between 85.8% and 106.7%. The relative standard deviations (RSD) of accuracy were lower than 7.86%. The optimized pretreatment conditions were as follows: 1.25 mg of 2,4-dinitrophenylhydrazine, derivatization time of 30 minutes, four cycles of extraction with acetonitrile, and three cycles of re-extraction with dichloromethane. Furthermore, the established method was used to evaluate the effects of three polyphenolic antioxidants: water-soluble gallic acid, water-oil amphipathic propyl gallate and water- and oil-insoluble quercetin on reducing the eight α,β-unsaturated aldehydes in linseed oil-in-water emulsion during storage. The results showed that α,β-unsaturated aldehydes accumulated rapidly during the storage of the emulsion,mainly malondialdehyde, 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal, while all three antioxidants significantly mitigated the accumulation of α,β-unsaturated aldehydes, with propyl gallate being the most effective. This method is a simple,efficient, environment-friendly, sensitive, and accurate one for the detection of α,β-unsaturated aldehydes generated during the processing, storage, and use of emulsion-based foods.