The development of polymer dielectric nanocomposite with high energy density and low charge-discharge loss retains primary project of polymer capacitor for portable electronics and embedding power system. In this work, we introduced hydroxyl groups on the barium titanate (BTO), which yielded hydrogen bonds with fluorine atoms in the P(VDF-TrFE) matrix. The released energy density for 10 wt% modified BTO/P(VDF-TrFE) nanocomposite film is 4.8 J/cm(3) with a charge-discharge efficiency of 74% at 150 MV/m due to transition of electroactive phase and improved interfacial polarization. This strategy provides simple approach for high electrical storage and commendable way for the commercial film capacitor.