The invention discloses a preparation method of a two-dimensional nano-sheet form alpha-Fe2O3 material. The preparation method is characterized in that ferric trichloride hexahydrate is placed in alumina crucible, then the material is placed in a tubular furnace equipped with an alundum tube, the tubular furnace is sealed and then inert gas is introduced, the material is heated to the temperatureof 380-450 DEG C under protection of inert gas, insulation is carried out for 8-24 hours, then the material is cooled to room temperature, and steps of washing with deionized water and drying are carried out to obtain the two-dimensional nano-sheet form alpha-Fe2O3 material. Compared with the prior art, a ferric trichloride hexahydrate reagent is subjected to thermal decomposition and oxidation under protection of the inert atmosphere to prepare the two-dimensional nano-sheet form alpha-Fe2O3 material, the used reagent has low cost, the preparation process is simple, large-scale preparation isrealized, and the morphology of obtained ferric oxide is the two-dimensional nano sheet.