||Vanadium oxides have been interested in electrochemical applications because of their low cost, intercalation property and effective electronic properties. However, the complicate synthesis process and low electronic conductivity of the vanadium oxides limit their application in energy storage. In this study, we introduce a facile and efficient sonochemical method to synthesize PEDOT-intercalated ammonium vanadate nanofiber composites (S-EANVF). The ammonium vanadate nanofiber (S-AVNF) and S-EAVNF were synthesized in 30 min and 3 hrs, respectively by using the sonochemical method. The S-EANVF exhibits improved electrical conductivity owing to the intercalated PEDOT molecules. The interplanar lattice space is expanded by the insertion of the PEDOT, which can facilitate the access of K+ ions into bulk lattice of vanadate. The combination of 1D-nanostructuring, lattice expansion and electrical conductivity enhancement results the highly improved pseudocapacitive performances.