The invention provides a method for recovering nonferrous metals, rare and noble metals and iron powder from steelmaking flue dust. The method comprises the following steps: mixing the steelmaking flue dust with a chlorination agent and a reducing agent, adding the obtained mixture to a tunnel furnace, and carrying out a two-stage reaction, wherein a primary stage reaction is a medium temperature chlorination reaction and allows nonferrous metals and precious metals to volatilize and enter flue gas, the flue gas is used as a nonferrous metal and precious metal extraction raw material after dusts are collected, and a secondary stage reaction is a high temperature reduction reaction and reduces iron into elemental iron which is discharged with kiln slag; and carrying out cooling, crushing and ball milling on the kiln slag to form a slag slurry with the granularity being smaller than 60 meshes, and carrying out magnetic separation to obtain the elemental iron powder and waste slag, wherein the iron content of the iron powder is greater than 86%, the iron powder can be used as commercial reduced iron powder, and the waste slag is sold to cement mills. The method allowing the chlorination and reduction metallurgy processes to be carried out in the tunnel furnace in a segmental manner has the advantages of process simplification, simplicity in operation, high thermal efficiency, low production cost and high comprehensive utilization rate, and is a new way for reasonable recovery of valuable metals in the steelmaking flue dust and high-efficiency resource utilization.