Abstract: A desulfurizer containing at least a composition of a highly concentrated amorphous iron oxide hydroxide as the active ingredient. A method for preparing a composition containing at least a highly concentrated amorphous iron oxide hydroxide. A method for regenerating the desulfurizer. The desulfurizer contains at least the composition of a highly concentrated amorphous iron oxide hydroxide as the active ingredient and a binder. The composition and the desulfurizer have a high sulfur capacity and can be regenerated. This saves resources and reduces environmental pollution. The method for regenerating the desulfurizer includes at least the following steps: a) mixing a solid soluble ferrous salt with a solid hydroxide, b) kneading the mixture and allowing it to react at temperatures not exceeding 90° C., c) drying in air, d) washing with water and filtering to yield a solid, and e) drying naturally or roasting the solid.