Electrospinning is a simple and cost-effective approach for the production of nanofibers and assemblies with controllable structures. In this work, based on sol-gel chemistry and the electrospinning technique, porphyrin-doped nanocomposite fibers with a form of nanofibrous membrane were successfully fabricated without the addition or help of polymers, and were demonstrated as novel fluorescence-based chemosensors for the rapid detection of trace vapor (10 ppb) of explosive. Due to a larger surface area and good gas permeability, these fluorescent nanofibrous membranes exhibit remarkable sensitivity to trace TNT vapor compared to tightly cross-linked silica films, but their sensitivity is strongly dependent upon the morphology and phase aggregation of the used nanofibers. Reducing the diameter and introducing a pore structure into nanofibers can considerably enhance the sensitivity of the resulting materials. The performed experiments suggest that the hierarchically structured, porphyrin- doped nanofibrous membranes are potentially very useful chemosensory materials for detecting trace explosives.