The invention relates to a preparation method of a PVB glue film and a dual-glass assembly packaged by employing the PVB glue film. The dual-glass assembly sequentially comprises a glass front panel,an upper-layer high-transmittance PVB glue film, a battery piece, a lower-layer high-reflection PVB glue film having a light wave conversion function and a glass back panel, wherein the upper-layer high-transmittance PVB glue film comprises high-transmittance PVB, a low-water permeation polymer and high-transmittance quartz powder, and the lower-layer high-reflection PVB glue film having the lightwave conversion function comprises PVB, a high-reflection material, a low-water permeation polymer and a light wave conversion material. The dual-glass assembly has the beneficial effects that the upper-layer high-transmittance PVB glue film has high light transmittance and moisture blocking performance and has a refractive index very similar to that of the front glass panel, so that sunlight isnot reflected at an interface layer of the front glass panel and the PVB glue film, and the sunlight incident rate is improved; and with the addition of the high-transmittance quartz powder in the upper-layer PVB and the high-reflection filler in the lower-layer PVB, the shrinkage rate of the PVB also can be reduced, the glass panel is prevented from being broken during the lamination process, andthe package finished rate is improved.