A new ternary composite of polyaniline/manganese dioxide/nitrogen, phosphorus co-doped carbon nanofiber (PANI/MnO2/NPCNF) has been synthesized by electrospinning technology and chemical oxidative reactions. The results show that MnO2 and PANI layers are uniformly coated on the surface of N, P co-doped CNF. The optimal ternary nanocomposite shows excellent electrochemical performance (587.3Fg−1 at 0.5Ag−1, ~63% capacitance retention from 0.5Ag−1 to 20Ag−1 and capacitance retention is ~84% after 1000cycles at 10Ag−1). That could be attributed to the synergistic effects contributed from individual components. The N, P co-doped CNF acts as carbon scaffold to facilitate the electron transform and improves the poor electrical conductivity of MnO2. The outer PANI layer could achieve high pseudo-capacitance, protect the MnO2 layer from reductive-dissolving and further heighten its electrochemical utilization.