In the presence of N,N'-dihexadecyl-N,N,N',N'-tetramethyl ethyl diamine bromide (21631) and fluorinated fatty alcohol polyoxyethylene ether as emulsifiers and ammonium persulfate as a water soluble free-radical initiator, a novel cationic fluorinated long alkyl polyacrylate FA-co-SLMA-co-DM-co-HPA (FSLDH) emulsion was prepared by copolymerization of perfluoroalkylethyl acrylate (FA) with octadecyl/dodecyl methacrylate (SLMA), dimethylaminoethyl methacrylate (DM) and 2-hydroxypropyl acrylate (HPA) in mass ratio of FA : SLMA : DM : HPA = 80 : 16.5 : 3 : 0.5 in aqueous medium. Chemical structure of FSLDH was characterized by infrared spectrum (IR) and 1H nuclear magnetic resonance (1H NMR), then film morphology as well as the hydrophobic performance property of FSLDH emulsion on cotton fiber substrates were investigated by atomic force microscope(AFM) and X-ray photoelectron spectroscopy (XPS) and other instruments. The experiment results indicate that the FSLDH emulsion could form a macroscopic smooth film on the treated cotton fiber surface. Four elements such as F, O, N, C could been examined on the treated cotton fiber surface. In addition, FSLDH could confer the treated cotton fabric with excellent water- and oil-repellency. When the dosage of FSLDH emulsion reached 5g in 100g H2O, the water- and oil-repellency of the treated cotton fabric respectively reached 90 and 5 degree, and the water static contact angle on the treated fabric surface also reached 144.9º.