Objective To investigate the effect of oil phase unsaturation degree on the performance of capsaicin emulsion to optimize its application efficacy in food systems.Methods Flaxseed oil (α-linolenic acid), sunflower oil (linoleic acid), and camellia oil (oleic acid) are selected to construct the emulsion systems. The particle size distribution, zeta potential, microstructure, in vitro digestion stability, and sensory characteristics are systematically analyzed.Results The camellia oil emulsion exhibits the largest value in average particle size of specific surface area, while the flaxseed oil emulsion demonstrates the smallest particle size and significantly higher absolute zeta potential values (P<0.01). Its compact interfacial structure maintains smaller particle sizes throughout the digestion process (P<0.01), ensuring the optimal protection of capsaicin. According to sensory evaluation, the flaxseed oil emulsion has the strongest spicy perception, potentially attributed to its high unsaturation degree.Conclusion The findings demonstrated that the stability of capsaicin emulsions correlates with the unsaturation degree of the oil phase. Highly unsaturated fatty acids enhance emulsion stability by forming viscoelastic interfacial films. Flaxseed oil, with the highest unsaturation degree, produces emulsion with the smallest particle size, most uniform distribution, and best emulsion stability and pungency intensity.