The invention discloses a bipolar threshold gate and a preparation method thereof, and belongs to the field of memory integration. The bipolar threshold gate comprises a SiO2 substrate prepared by oxidation, an adhesive layer, a lower electrode, an insulating medium layer, an oxygen storage layer and an upper electrode, and the adhesive layer, the lower electrode, the insulating medium layer, theoxygen storage layer and the upper electrode are arranged above the substrate, wherein the oxygen storage layer is an oxide layer formed by annealing oxidation, which respectively supplies and storesoxygen vacancies for the formation and fracture of a conductive filament; and the oxygen storage layer can be used as a barrier layer to prevent the ion implantation phenomenon of the upper electrodeon the resistance change layer in the sputtering process. The insulating medium layer material is a binary oxide, and the stoichiometric ratio of the binary oxide to oxygen atoms of the oxygen storagelayer is different. The bipolar threshold gate has the function of bidirectional gating, can effectively inhibit leakage current in a three-dimensional structure and a cross array resistance random access memory, and is a gating device with great application prospect.