The invention provides a nanoemulsion adjuvant and a preparation method thereof, which are composed of the following components: a continuous aqueous phase containing H2O molecules, an oil phase material containing fats and oils, and an emulsion system for stabilizing the interface between the continuous aqueous phase and the oil phase, and the emulsion system is an emulsifier mixture. The adjuvant is characterized in that the emulsion system does not contain an ionic emulsifier and the particle size of the emulsion is between 20 and 200 nanometers. The use of the nanoemulsion adjuvant can prevent toxicity and possible harm of ionic emulsifiers to human cells, and provide a vaccine preparation capable of eliciting a high degree of immune response.
