•A branch fluorinated cationic surfactant was synthesized and characterized.•The surface activities of BFCS were investigated.•BFCS exhibited better surfactant properties.A novel branch fluorinated cationic surfactant trimethyl-(2-{4-[3,4,4,4-tetrafluoro-2-(1,2,2,2-tetra-fluoro-1-trifluoromethyl-ethyl)-1,3-bis-trifluoromethyl-but-1-enyloxy]-benzenesulfonylamino}-ethyl)-ammonium iodide (BFCS) was synthesized successfully, and it's structure was characterized by FTIR, 1H NMR, 13C NMR, 19F NMR, MS. The surface activities of BFCS, the effect of temperature, electrolyte and combination with hydrocarbon surfactant were investigated. The results showed that BFCS exhibited excellent surface activity and combined properties.Trimethyl-(2-{4-[3,4,4,4-tetrafluoro-2-(1,2,2,2-tetra-fluoro-1-trifluoromethyl-ethyl)-1,3-bis-trifluoromethyl-but-1-enyloxy]-benzenesulfonylamino}-ethyl)-ammonium iodide (BFCS) was synthesized. Its structure was well characterized and BFCS exhibited excellent surface activity and combined properties.