Macroporous membranes with robust waterproofness, breathability and mechanical properties have attracted a great deal of attention. However, great challenges still remained in developing an effective and cost-efficient method to fabricate such materials. In this study, polyacrylonitrile (PAN)/fluorinated polyurethane (FPU) nanofibrous composite membranes with enhanced waterproof and breathable performance were fabricated by combination of electrospinning and heat post-treatment. The introduction of FPU enriched the nanofibrous membranes with superhydrophobic surface with water contact angle of 151, optimized pore size and porosity. Moreover, the relationship among hydrostatic pressure, pore structure and surface wettability has proven to be in accordance with Young-Laplace equation. By employing the heat post-treatment, the pristine PAN/FPU composite membranes were endowed with physically adhesion structure, thereby significantly improved the waterproof-breathable performance as well as the mechanical property. Owing to these effects, the resulting thermal treated PAN/FPU composite membranes exhibited the integrated properties of high hydrostatic pressure (114.6 kPa), water vapor transmission rate (10.1 kg m(-2) d(-1)) and good tensile strength (9.4 MPa). Furthermore, the reinforced PAN/FPU nanofibrous composite membranes have great potential to be used as functional materials for fabricating separation media, filter, outdoor sportswear, chemical protective clothing, and army combat uniforms. (C) 2015 Elsevier B.V. All rights reserved.