The invention discloses a method of preparing a barium titanate-doped organic metal halide perovskite thin film, which belongs to the preparation field of semiconductor optoelectronic materials and hybrid perovskite solar cells. A doping method is adopted to add the barium titanate material to the perovskite material and uniform dispersion in the perovskite solution is carried out; and a spin coating method is adopted, spin coating of a barium titanate-containing perovskite layer on a mesoporous titanium dioxide thin film is carried out and an optical absorption layer material for the solar cell is formed. Through the method of carrying out doping to improve the ferroelectric polarity of the perovskite, the barium titanate material with the ferroelectricity is added to the perovskite layer, the inner electric field polarization state when photoelectric effects happen to the solar cell is improved, and the perovskite solar cell stability and the photoelectric conversion efficiency are improved.