Abstract: In order to prepare a more stable coconut oil emulsion, sodium caseinate (SC) and xanthan gum (XG) were combined as emulsifiers, and coconut oil was used as the oil phase, and the coconut oil emulsion was prepared by ultrasonic method. The average droplet sizes, Zeta-potentials, centrifugal stability and turbidity of emulsions were characterized to choose reasonable parameters concerning the ultrasonic treatment time, ultrasonic treatment power, mass fraction of oil phase, and pH values of aqueous phase, by the single factor test. The Box-Behnken response surface methodology (RSM) was used to optimize the parameter (including ultrasonic treatment power, ultrasonic treatment time, and pH values of aqueous phase) to prepare the stable emulsions. The optimal conditions were obtained as follows: Ultrasonic power 480 W, ultrasonic time 18 min, and pH7 of aqueous phase. Under this condition, the smallest droplets size of emulsions was obtained 304.5±13.2 nm. All coconut oil-based emulsions showed an extraordinary stability with heat treatment temperature of 40~90 ℃, pH6~8 and ion concentration of 0~0.5 mol/L, and the emulsion remained stable after three freeze-thaw cycles. The findings would provide a facile strategy to prepare stable coconut oil-based emulsions in the food processing.