The invention provides a mold with a steel structure. The mold comprises a base. The upper part of the base is elliptic. A casing tool is arranged at the center of the base, and is cylindrical. A circular groove, which is collinear with the axial lead of the casing tool, is formed in the casing tool. A mold core is arranged at the center of the bottom end of the circular groove, and takes the shape of a regular hexagonal prism. A positioning hole, which is collinear with the axial lead of the mold core, is formed at the center of the mold core. A plurality of grooves are uniformly formed in the casing tool in the circumference direction. Two handles are symmetrically arranged on the base on two sides of the casing tool. A battery mounting mold, that is, the mold with the steel structure has the advantages that the principle is simple, the structure is compact, the mold is convenient to use, invested for once, and durable, the production cost is low, the manpower source is saved, the labor intensity is reduced, the working efficiency is improved, the fixed sizes of lithium batteries are broken, the economic benefits are improved, and the market prospect is wide.