The film morphology of dodecyl/carboxyl modified polysiloxane (RCAS) on cotton fabric or the silicon wafer was investigated by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The results showed that RCAS formed a relatively smooth film on the fabric surface. With the fabric terated by RCAS, the grooves on the fabric surface disappeared. What’s more, RCAS formed a micromorphology inhomogeneous and unsmooth film on the silicon wafer.There were many high or low bright peaks distributed at random on the film surface, especially as the field was 2×2μm2 and the date scale was 5nm in AFM observation. The application performance of RCAS emulsion and compounded emulsion on cotton fabric was also investigated.The application results indicated that RCAS emulsion and compounded emulsion provided the treated fabrics with good softness，compared to untreated fabric. Moreover, the bigger the concentration of RCAS emulsion in the compounded emulsion,the better the hydrophilicity and whiteness of the treated fabrics.Whereas the softness of the treated fabrics decreased.