Citrus essential oil, as a natural extract with a broad-spectrum antibacterial effect, can effectively inhibit the growth of food-borne pathogens, but its wide application is limited due to its easy volatilization and poor water solubility. In this study, through the inhibition zone diamater test of three kinds of citrus (bergamot, sweet orange, honey pomelo) essential oilswith good antibacterial effect on Staphylococcus aureus wasusedas the oil phase. Tween 80 was used as the emulsifier, with deionized water used as the water phase, and the nanoemulsions was prepared by phase transformation method. According to the pseudo-ternary phase diagrams, the formulas of three citrus essential oil nanoemulsions were obtained， i. e. 6% essential oil, 24% Tween 80 and 70% deionized water. The average particle sizes of the prepared nano-emulsions were between 10~20 nm, and the particle size distributionswere uniform.The inhibition zone diameter test and the minimum inhibition concentration test showed that the antibacterial activity of the three citrus essential oils into nano-emulsions was improved, among which the bergamot essential oil nanoemulsion showed the strongest antibacterial effect against S. aureus, and the minimum inhibitory concentration and the minimum bactericidal concentration were both 3.75 mg/mL. The inhibitory activity was 2.5 times that of the pure essential oil.Scanning electron microscopy results showed that, compared with pure essential oil, bergamot essential oil nano-emulsion damaged the bacterial structure more significantly. This showed that the bergamot essential oil nano-emulsion had a good antibacterial effect on the food-borne pathogen S. aureus.