The invention discloses a method for treating iron-containing dust in an iron and steel plant by using a cupola furnace, belonging to the technical field of iron making. The method is characterized by comprising the following steps of: blending, uniformly mixing, briquetting and maintaining raw materials including dust in the iron and steel plant, a carbonaceous reducing agent, a bonder and an additive, and then putting the raw materials into the cupola furnace for iron making, wherein the carbon content of carbon-containing pellets prepared by briquetting raw materials of various iron-containing dust in the iron and steel plant is about 10%, the compressive strength of the maintained pellets is greater than 1000N per each pellet, and the pellets are distributed into the cupola furnace for iron making through a material distribution system; and preheating blast through a hot blast furnace, preheating the wind temperature from a normal temperature to about 500-1200 DEG C, and enriching oxygen by 1-5% in the blast to achieve the aims of improving the smelting strength, increasing the output and reducing the coke ratio. By adopting the method, the dust of the iron and steel plant can be recycled to achieve the aims of saving energy, reducing emission and reducing environmental pollution, so that the method has good economic and social benefits.