The invention discloses an equipment device and a preparation method for carrying out catalytic oxidation on ferrous iron to form ferric iron, and relates to the technical field of a water treatment agent. The equipment device comprises a reaction tower. The reaction tower comprises a reaction region, a raw material region and an aeration region, wherein the reaction region comprises a reaction channel; a plurality of tower plates are arranged on the reaction channel; discharge holes are formed in the reaction channel; the raw material region comprises a raw material pool; a connected raw material pipe is arranged on the raw material pool; a booster pump is arranged on the raw material pipe; the tail end of the raw material pipe is communicated into the tower plate at the uppermost part; the aeration region comprises a swirl type gas pump; a connected gas pipe is arranged on the swirl type gas pump; the gas pipe is communicated into the tower plate at the bottommost part. The preparation method for carrying out catalytic oxidation on the ferrous iron to form the ferric iron comprises: preparation of reaction raw materials: preparation of Fe2+ solution and preparation of reaction stock solution; aeration of the reaction raw materials and the reaction stock solution. Based on the preparation method adopting a preparation device for carrying out catalytic oxidation by microorganisms to form ferric iron by using the ferrous iron as the raw material, the equipment carries out catalytic oxidation by the microorganisms so as to carry out catalytic oxidation on the ferrous iron to form the ferric iron.