The invention discloses a method for preparing inorganic slag fibers by using iron tailings, and belongs to the technical field of inorganic nonmetallic material preparation. The method comprises the following steps of: mixing the iron tailings and metallurgical slag, heating the mixture to be a melted state, and preparing the inorganic slag fibers by blowing or throwing, wherein the mixture in the melted state contains 30 to 90 weight percent of iron tailings and 70 to 10 weight percent of blast furnace slag. The method has simple and feasible process, is convenient to implement, realizes comprehensive utilization of different industrial wastes such as the iron tailings, the metallurgical slag and the like, improves the additional value of the comprehensive utilization of the iron tailings, and has good economic and environmental benefits.