The invention discloses a self-tight pervoskite solar cell and a preparation method. The self-tight pervoskite solar cell comprises a transparent substrate, an electrode, a charge transporting layer,a pervoskite active layer, a self-tightness layer, a charge transporting layer, and an electrode; the material adopted by the self-tightness layer is the high-polymer material with hot melting, barrier property and self-adhesion, such as ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylate copolymer, ethylene-acetate-vinyl alcohol ternary copolymer, polyamide, and polyimide, and the high-polymer containing like structures and characteristics. The self-tightness layer can be prepared on the surface of the pervoskite through an anti-solvent or spinning-coating method, and is prepared after heating and annealing. The pervoskite solar cell prepared by the invention can be stored in the water under an unencapsulation condition; since the self-tightness layer has good adhesion effect, the solar cell has excellent anti-bending performance, the stability of the device in the actual operation is greatly improved.