The polarization effect of ferroelectric films and the hot electrons induced by the nonradioactive damping of surface plasmon in metal micro-nano structures can be used to improve the photoelectric conversion efficiency of traditional ferroelectric films, which has broad application in photovoltaics, photocatalysis, and photoelectric detection. In this paper, uniform BiFeO₃ films are fabricated by the sol-gel method, and the electron beam thermal evaporation is employed to make the Au nanoparticles deposited on the upper and lower surfaces, so as to obtain Au/BiFeO₃ composite films. The results show that compared with the pure BiFeO₃ films, the light absorption of the composite films with Au nanoparticles in the visible region is significantly enhanced, and the photocurrent density is also increased. In addition, the interface barrier of ferroelectric thin films is controlled by the polarization effect of ferroelectric thin films, so as to control the transfer of hot electrons in Au nanoparticles and photogenerated carriers in BiFeO₃ thin films, realizing the manipulation of the photocurrent polarity in composite films.