Electrospun nanofibrous film doped with it fluorescent conjugated polymer P was developed as a sensory device for detection of the explosive 2,4-dinitrotoluene (DNT). Polymer P obtained through a Sonogashira cross-coupling polymerization showed high affinity and excellent fluorescence quenching property toward electro-deficient compound DNT in solution. A versatile and effective electrospinning technique, which effectively reduced aggregation and fluorescence self-quenching of the conjugated polymers in thin film by the traditional spin-casting, was successfully employed to develop explosive-sensing nanofibrous devices. By doping with polystyrene as supporting matrix and subsequent electrospinning, the obtained fluorescent nanofibrous film exhibited remarkable sensitivity to trace DNT vapor due to a large surface area-to-volume ratio and unique porous structure. The sensitivity of the device was further improved by introducing secondary pores into the nanofibers through addition of a surfactant, sodium dodecyl sulfate, as it porogen agent. This strategy can provide a platform for other conjugated polymers using electrospinning technology to construct new optical chemo- and biosensors.