The present disclosure relates to a high light transmittance photovoltaic encapsulating material, which is prepared by the following process: subjecting 100 mass parts of a photovoltaic encapsulating material matrix resin or a graft-modified matrix resin, 0.001 to 5 mass parts of an oxygen- or sulfur-containing compound, 0.01 to 10 mass parts of a reactive plasticize 0.01 to 1.5 mass parts of an initiator, 0.01 to 10 mass parts of an assistant cross-linker, 0.1 to 3.0 mass parts of a silane coupling agent, 0.1 to 0.4 mass parts of an ultraviolet light absorber, and 0.1 to 1.0 mass part of light stabilizer to pre-mixing, melt extrusion, film casting, cooling, slitting, and coiling. The light transmittance of the photovoltaic encapsulating material is improved, and the refractive indexes of glass/front-layer encapsulating material/cell match each other, thereby increasing the sunlight utilization ratio of a module, and optimizing the photoelectric conversion efficiency of the module.