The invention discloses an organic solar cell with a metal mesh nested heterojunction and a preparation method thereof, which relates to the field of organic solar cells, including a transparent substrate, a transparent anode electrode, a hole transport layer, a donor material layer, an ultra-thin The mesh metal layer, the acceptor material layer, the electron buffer layer and the cathode electrode are located between the donor material layer and the acceptor material layer with a mesh-shaped continuous metal mesh nesting layer. The metal mesh layer can form a local Schottky junction with the N-type acceptor material layer. On the basis of the original heterojunction, a double built-in electric field is formed, which is conducive to the stepwise diffusion of electrons from the n-type material to the p-type material. Holes diffuse from p-type materials to n-type materials, increasing the thickness of the heterojunction structure, improving the separation efficiency of photogenerated excitons, and ultimately improving the conversion efficiency of organic solar cells.