The present invention discloses a fluorine-containing emulsifier as well as anionic fluorine-containing emulsion prepared based on the emulsifier and a method, and belongs to the technical field of fine chemical preparation. Fluorocarbon emulsion containing a sulfonic acid group consists of the following raw materials: fluorine-containing acrylate, butyl acrylate, styrene, acrylic acid or 2-acrylamide-2-methylpropane sulfonic acid, an emulsifier, an initiator and water. The preparation comprises: carrying out high speed shearing on all types of the raw materials (wherein 70% of the water is added, and the remaining 30% of the water is kept for later use) for 30 minutes, taking the remaining 30% of water and 5% of the pre-emulsion after obtaining pre-emulsion, raising the temperature of the water and the pre-emulsion to 50-80 DEG C under stirring, and starting to carry out heat preservation; and starting to dropwise add the remaining pre-emulsion after carrying out the heat preservation for 30 minutes, enabling the remaining pre-emulsion to react for 5-25 hours, cooling the remaining pre-emulsion to the room temperature, and discharging the cooled pre-emulsion, thereby preparing the anionic fluorine-containing emulsion . According to the present invention, the emulsifier in the emulsion directly reacts with a polymeric monomer, thereby avoiding a migration problem of a conventional emulsifier; and meanwhile the water is used as a dispersion medium, so that no organic solvent is contained, resources are saved, and environment-friendly requirements are satisfied..