The invention discloses a high-brightness prism laminating film and a preparation method thereof, which successively comprise a back coating layer, a PET layer, a first prism layer, a second prism layer, a first prism layer and a second prism layer from bottom to top The upper array is provided with prisms, the apex angles of the prisms of the first prism layer are inserted into the lower surface of the second prism layer, the longitudinal extension direction of the prisms of the first prism layer and the longitudinal extension direction of the prisms of the second prism layer are at an angle of 90°, The prism height of the first prism layer is 20-44 μm, the height difference of each prism apex of the first prism layer is 0.5-2 μm, the prism height of the second prism layer is 20-44 μm, and each prism of the second prism layer is arranged at the same height , The haze of the back coat is 2-10%. The invention simplifies the double-layer PET layer structure in the prior art, reduces the light interference phenomenon in the whole module, thereby reduces the light loss, significantly improves the brightness of the prism bonding film, simplifies the preparation process and assembly process, and saves cost.