A novel comb-like polysiloxane (QPEPS) bearing dimethyldodecyl quaternary ammonium polyether groups (QPEs) was synthesized by reaction of epoxy polyether polysiloxane, which was prepared from polymethylhydrosiloxane (PHMS) and allyl polyether epoxy (APEE500) via hydrosilylation, with N,N-dimethyldodecylamine (DMDA) in the presence of acetic acid (HAc). Chemical structure, film morphology, and performance of the synthesized polysiloxane on cotton and its mimic substrates were investigated by Fourier transform infrared spectrum, nuclear magnetic resonance spectrum, field emission scanning electron microscopy, atomic force microscopy, and so on. As expected, the QPEPS was easily emulsified into a clear, uniform micro-emulsion with a mean size of about 20 nm. Since the presence of a large number of cationic QPEs pendant in the side chains, the QPEPS exhibited microscopic inhomogeneous morphology with many pinnacles projected on the film surface. As a result, the root mean square roughness (Rq) of the QPEPS film reached 0.615 nm in 2 µm × 2 µm scanning field and the largest height of the pinnacles achieved 7.618 nm. And under the influence of the QPEs, the QPEPS provided the treated fabrics with not only very soft handle, but also excellent hygroscopicity. And the wettability of the treated fabrics reached 1–3 s. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40612.