In this work, a new bimodal fiber diameter distributed structure composed of polyurethane (PU) and poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) hybrid nanofibers was synthesized and used as a breathable-windproof membrane (BWM). Graphene oxide (GO) was compounded with AMPS through polymerization process to increase the membrane performance. Water vapor permeability (WVP), air permeability (AP), and tensile strength at break were evaluated as BWMs performance. The effects of PU and PAMPS fiber density and GO loading on the membrane performance were modeled and analyzed using the response surface methodology (RSM). The results show that when PU fiber density declined and GO loading increased, WVP of membranes improved. Also, an increase in PU and PAMPS coverage density led to a decrease in AP. Tensile strength at break increased as PU fiber density and GO loading rose. RSM also predicted that with using 6.07g/m(2) PU fiber density, 2.40g/m(2) PAMPS fiber density, and 2% GO loading, the optimum performance of BWM, that is, the maximum order of tensile strength (18.45MPa) and WVP (848.22g/m(2)/day) and the minimum order of AP (15.66 lit/m(2)/s), can be obtained. The results of experimental tests are in good agreement with predicted values by RSM.