We Have fabricated a holographic polymer-dispersed liquid crystal (HPDLC) thin film, which is composed of multifunctional acrylate monomer blended with the nematic liquid crystal mixture, and then investigated the real-time diffraction efficiencies for various amounts of liquid crystals and applied AC electric fields. It is experimentally shown that the holographic gratings recorded in the HPDLC film can be reversibly erased and reconstructed by switching on and off an appropriate applied AC electric field. By use of these electro-optic properties we have developed bifocal holographic lenses having two different focal lengths of 30cm and 40 cm.