The invention discloses an FK102 ligand modified perovskite solar cell and a preparation method of a perovskite layer thereof. The perovskite solar cell comprises an electron transmission layer, perovskite, a hole transmission layer and an electrode, wherein a material forming a modification layer is selected from an FK102 ligand. By the interface modification material, Co<3+> in the hole transmission layer can be prevented from diffusing towards the perovskite, so that the decomposition of the perovskite by Co<3+> is prevented, the defect mode is reduced, reverse recombination of charges is prevented, and the charge injection efficiency is improved; and moreover, the material is low in cost, the operation method is simple and is easy to control, and a new idea is provided for research ofinterface behavior of the perovskite solar cell.