Disclosed are an MPS diode device and a preparation method therefor. The MPS diode device comprises a plurality of cells arranged in parallel, wherein each cell comprises a cathode electrode, and a substrate, epitaxial layer, buffer layer, and anode electrode that are formed in succession on the cathode electrode; two active regions are formed on the side of the epitaxial layer away from the substrate; the width of forbidden band of the buffer layer is greater than the width of forbidden band of the epitaxial layer, and a material of the buffer layer and a material of the epitaxial layer are allotropes; and first openings are formed at the positions in the buffer layer opposite to the active regions, and an ohmic metal layer is formed in the first openings.