Provided is an oil-in-water emulsion containing no surfactant. The emulsion comprises a metabolizable oil phase, a water phase, and oil-water amphipathic solid particles with biocompatibility dispersed in the water phase, wherein the oil phase comprises squalene or/and tocol the water phase is any or a combination of at least two of the group consisting of purified water, water for injection, glycerine solutions, buffered saline solutions or clinically transfusable solutions and the solid particles have an average particle size of nanometer to micron level. The emulsion can be used as a vaccine adjuvant, a medicine deliverer or a slow/controlled release carrier, avoid the use of surfactants and reduce harm to human body and environmental pollution.
