The invention discloses a preparation method of a high-magnification and long-service-life rechargeable room-temperature sodium battery. A ferrous disulfide microsphere is used as a cathode material, a sodium sheet is used as an anode, a diaphragm is a three-layer membrane formed by polyethylene, polypropylene and polyethylene, or glass fiber paper, an electrolyte is an ether type electrolyte containing a sodium salt; a conductive agent used by coating a cathode plate is formed from one or more of acetylene black, Super P, KS-6, a carbon nano tube, graphene, petroleum coke and the like; a binder is polyvinylidene fluoride or sodium carboxymethylcellulose; a solvent is N-methyl pyrrolidone or water; a current collector is foamed nickel, a copper sheet, foamed copper or an aluminum sheet. The preparation method has the advantages that the ferrous disulfide microsphere is simply and conveniently prepared, and the purity is high. Meanwhile, due to a morphologic advantage of a micro-nanometer structure, the high-magnification and long-service-life rechargeable room-temperature sodium battery is relatively high in specific capacity and cyclic stability and excellent in magnification performance. Therefore, a ferrous/sodium disulfide secondary battery is expected to be in commercialized production, and becomes the next-generation large-scale energy storage battery.