The invention belongs to the technical field of polymer solar cells, and particularly relates to an organic solar cell based on the polyfluorene cathode interface self-assembly anode plasma resonance effect and a preparation method of the organic solar cell. According to the method, an amphipathic polyfluorene material with high conductivity serves a cathode transmission layer, interface contact with ITO is increased through self-assembly of the cathode transmission layer, the cathode transmission layer replaces a traditional TiO2 or ZnO inorganic transmission layer, interface combination is reduced, and the performance of the organic solar cell is improved; meanwhile, a vacuum evaporation method is adopted for directly arranging a layer of gold nanoparticles on an active layer in an evaporation mode, light scattering is increased by utilizing the surface plasma effect of the layer of gold nanoparticles, the light path is increased, then the light utilization rate is increased, and thus the performance of a device is improved. The efficiency of the organic solar cell is effectively improved through the method, and the method is of great reference significance for nanoimprint lithography and development of organic solar cells in the future.