The invention belongs to the field of veterinary drugs and particularly relates to a method of preparing florfenicol submicron emulsion by using a nonpolar support, comprising: weighing, in percent by weight: 5-10% of florfenicol, 20-30% of a surfactant, 5-15% of oil and the balance of water, wherein the surfactant is one, or a combination, of polyoxyethylene 40 hydrogenated castor oil RH-40 and polyoxyethylene 30 hydrogenated castor oil RH-30 and the oil is one, or a combination, of diethyl malonate, diacetyl monoglyceride and acetyl tributyl citrate; adding the oil into the florfenicol, stirring, adding the surfactant until the florfenicol is fully dissolved, and continuing to stir well; adding water to liquid medicine that is stirred well, and stirring while adding the water until a uniformly transparent system is formed to obtain the florfenicol submicron emulsion. The nonpolar support is utilized and is mixed with water to provide the unique advantage that a drug never separates out, and the problem that the florfenicol is unable to be dosed with water and particularly the problem that a doser used in large-scale farming groups has difficulty of dosing are overcome.