A polymerizable anionic emulsifier was successfully prepared by using dimer acid derived from nature，latex with this polymerizable anionic emulsifier used exclusively was prepared through semi-continuous seeded emulsion polymerization. Its emulsification and the surface tension were mensurated. The latex particle size and chemical composition were investigated by size analysis, nuclear magnetic resonance (H-NMR) and surface tension. Test results showed that this new polymerizable anionic emulsifier had better emulsifying capacity, compared with the commonly used anionic emulsifier sodium dodecyl sulfate (SDS), the critical micelle concentration of the polymerizable anionic emulsifier was 28.6 mmol / L. H-NMR and surface tension tests indicated that the polymerizable anionic emulsifier might have copolymerized with the monomer in free radical polymerization. The water absorption ratio and Zeta potential of the emulsion prepared with this polymerizable anionic emulsifier were only 2.81% after 24 hours and -70 to -60 mV.