The invention discloses a perovskite solar cell and a preparation method thereof. The perovskite solar cell comprises a conductive glass layer, a compact titanium dioxide film, a porous titanium dioxide film, a methylamine lead iodine polycrystalline film, a hole-transport material layer and a metal electrode layer in sequence. The perovskite solar cell is characterized in that the porous titanium dioxide film is Zn-doped, and after doping, mole ratio between zinc atoms and titanium atoms is 0.1%-0.4%:1. The perovskite solar cell has the advantages that the Zn-doped porous titanium dioxide is utilized as a photo anode of the perovskite solar cell; a titanium dioxide conduction band can be changed through Zn-doping, and the titanium dioxide conduction band is allowed to move down, so that a gap between a methylamine lead iodine conduction band serving as a perovskite light absorption layer and Zn-doped porous titanium dioxide conduction band is enlarged, electrons are allowed to be easier to inject and pass, and photoelectric conversion efficiency of the perovskite solar cell can be improved.