NOVELTY - Preparing polypyrrole nanofiber comprises dispersing benzothiadiazole and 4,5,6,7-tetrabromo-2-azabenzimidazole as fluorescence agent in deionized water and then ultrasonically vibrating to obtain homogeneous solution, adding pyrrole monomer into decompression distillation device at normal pressure, heating the homogeneous solution and then distilling to obtain pure pyrrole monomer, mixing fluorescent agent and pyrrole monomer under the protection of nitrogen, mixing pure pyrrole monomer aqueous solution with fluorescence agent, and ultrasonically vibrating and reacting.    USE - The method is useful for preparing polypyrrole nanofiber (claimed), which is useful in multifunctional anti-static conductive coating, display material, micro-nano material, nano solar cell and light-emitting device.    ADVANTAGE - The method allows simple preparation of the polypyrrole nanofiber in an eco-friendly manner with good flexibility and conductivity, strong stability and excellent fluorescent property.    DETAILED DESCRIPTION - Preparing polypyrrole nanofiber comprises dispersing benzothiadiazole and 4,5,6,7-tetrabromo-2-azabenzimidazole as fluorescence agent in deionized water according to weight ratio of 1:10-20 and then ultrasonically vibrating for 1 hour to obtain homogeneous solution, adding pyrrole monomer into decompression distillation device at normal pressure, heating the homogeneous solution at 60 degrees C and then distilling to obtain pure pyrrole monomer, mixing fluorescent agent and pyrrole monomer under the protection of nitrogen, where the volume ratio of pure pyrrole monomer and deionized water is 1:20-50 to obtain pure pyrrole monomer aqueous solution, mixing pure pyrrole monomer aqueous solution with fluorescence agent according to volume ratio of 1:2, ultrasonically vibrating and reacting for 12 hours to obtain mixed solution, adding oxidizing agent and 20-30 wt.% of ferric chloride solution into mixed solution under the protection of nitrogen, oxidizing polymerization initiator to form polypyrrole monomer, adding benzothiadiazole and 4,5,6,7-tetrabromo-2-azabenzimidazole into a high molecular chain to form a polarized or dual polarized, dissolving polypyrrole in water to form precipitate, filtering the filtrate and then washing until it is colorless with diethyl ether for 2-3 times to obtain polypyrrole nanofiber sample with ethanol and drying the polypyrrole nanofiber sample in vacuum drying box for 24 hours to obtain black powder, where the polypyrrole nanofiber has average diameter of 100 nm.