A new linear-chain polyether-aminosiloxane （LPEAS) was synthesized by the reaction of epoxy polyether terminated polydimethylsiloxane with N, N-dimethyl-propanediamine. The Chemical structure of LPEAS was characterized by IR and 1H-NMR.Then the particle sizes, particle sizes distribution were investigated by transmission electron microscope (TEM) and other instruments. The effects of its viscosity, amino value and the amount of the emulsion on the performance of treatment of cotton fabrics were also studied. The results showed that average particle size of LPEAS emulsion was only 27nm, cotton fabric featured hydrophilicity improved, the bending rigidity of fabric decreased, and the whiteness of the fabrics remained the same,when the viscosity of LPEAS was 0.950 Pa•s, amino value was 0.3 mmo1/g ,the amount of the emulsion was 10kg/t，and curing at 100℃for 5min following 160℃for 30 seconds.