The invention relates to an electron beam irradiation synthesis method of nanometer zinc selenide quantum dot powder, belonging to the technical field of preparation process of nanometer inorganic compound semiconductor material. The invention adopts zinc nitrate hexahydrate and sodium selenite as raw materials, and the molar concentration ratio of two raw materials is 1:1-1:2; chelating agent ethylene diamine tetraacetic acid (EDTA) and oxidative radical OH. scavenger isopropyl alcohol are added; the mixture is fully stirred to be evenly mixed; then, the mixed liquor is filled in a sealed container to be irradiated by the electron beam produced by an electron accelerator of 2.5MeV and 6-7mA with the irradiation dose of 14-42Mrad and irradiation time of 10-30 minutes; finally, an irradiated reaction product is evaporated in a rotating mode, concentrated and dialyzed and is separated by a high speed centrifuge; the obtained reaction product is washed with alcohol several times and dried in vacuum to obtain white zinc selenide quantum dot powder. The invention has simple and convenient method, quick synthesis, favorable safety and no pollution and is favorable for environment protection.