The invention provides a chargeable molten salt iron-air battery and a preparation method, and mainly aims at providing a molten salt iron-air battery capable of stably running at medium and low temperature. The chargeable molten salt iron-air battery is characterized in that a positive current collector is platinum or nickel; a negative current collector is iron or iron alloy, and comprises a negative active material layer; the negative active material layer is formed by iron particles which are obtained by electro-deposition of an iron compound on the negative current collector during charging; electrolyte is molten salt electrolyte, and comprises the following components by percentage: 5%-20% of KCl, 20%-60% of LiCl and 15%-55% of LiOH; the working state is a molten state; the sum of the KCl, the LiCl and the LiOH is 100%; the active material layer of the positive current collector contains a catalyst; and the catalyst is a platinum catalyst, a nickel oxide catalyst, a cobaltosic oxide catalyst or a manganese dioxide catalyst or a composition of the platinum catalyst, the nickel oxide catalyst, the cobaltosic oxide catalyst and the manganese dioxide catalyst.