Functional core-shell structured composite nanofibers were prepared by electrospinning two polymer solutions in a coaxial system. The core-shell structured nanofibers were comprised of varying concentrations of polyurethane (PU, shell) and a Nylon-6 (core). The resultant nanofibers were characterized by means of scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy and tensile mechanical test. Furthermore, water vapor transmission rate and pliability of cotton fabrics coated with non-woven mats of the core-shell structured nanofibers were also measured. The results indicated that it is feasible to attach composite nanofibers onto a textile substrate.