The environmentally friendliness and biodegradability of fluorinated surfactants are increasingly important and the use of long-chain (≥C8) perfluorinated surfactants will be evidently forbidden in future. In this work, a cationic fluorinated surfactant, N-[3-(dimethylamino)propyl] butanesulfonamide monohydrochloride (C4F9SO2NH(CH2)3-NH(CH3)+2Cl-, abbr. PFB-MC) based on a short fluorocarbon chain, perfluorobutyl, was synthesized. This surfactant was effective in acidic environments. It shows very high surface activity and its lowest surface tension (19.80 mN·m-1) in aqueous solution can be compared with the common fluorinated surfactants. The surface tension-logarithm of concentration (γ-lgc) curve of PFB-MC at a constant pH (pH=2.6-2.7) and the effect of salt addition on surface tension ([NaCl]=0.1 mol·L-1) at this pH were obtained by surface tension measurement. The effect of pH on the surface tension of these PFB-MC solutions below and above critical micelle concentration (cmc) was also studied.