The invention provides a method for extracting iron by utilizing nickel slag and preparing fibers. The method comprises the following steps of: adding a reducing agent and auxiliary materials to nickel slag discharged in a nickel smelting process to reduce oxides of iron in the nickel slag into iron; after the iron is separated, adding an additive to the remaining molten nickel slag; and blowing or throwing the molten mixture with the additive through high-speed air or a centrifugation throwing machine to prepare inorganic fibers. According to the method, on the basis of melting and reducing the thermal nickel slag for refining the iron, the remaining slag is used as a main raw material to prepare the inorganic slag fibers, and the waste nickel slag is changed into valuable materials and recycled, so that the sensible heat of the thermal nickel slag is sufficiently utilized, and the energy consumption in the processes of refining the iron from the nickel slag and producing the fibers is reduced. The main components of the prepared inorganic nickel slag fibers are SiO2, Al2O3 and the like, and the prepared inorganic nickel slag fibers belong to high-temperature inorganic fibers andcan be widely applied to the fields of pipe warm preservation, industrial fire resistance and warm preservation and the like.