A catalyst, including a molecular sieve carrier and an active component. The active component includes: iron, manganese, copper, and a basic promoter potassium. The molecular sieve carrier is a cerium salt and/or praseodymium salt modified-aluminosilicate molecular sieve carrier and/or silica-rich molecular sieve carrier. A method for preparing a catalyst for Fischer-Tropsch synthesis, includes: 1) fully dissolving a ferric salt, a manganese salt, a copper salt, and an alkali or a salt containing potassium element in water to yield an aqueous solution, stirring and adding sodium lauryl sulfate to the aqueous solution, and continuing stirring to yield a uniform solution; and impregnating a modified molecular sieve in the uniform solution to yield a mixed solution; and 2) drying and calcining the mixed solution to yield the catalyst.