The invention relates to the field of complex utilization of solid waste resources of iron and steel plants and particularly relates to a method for preparing electric zinc from zinc-containing smoke dust of an iron and steel plant. The method comprises the following steps: in a slightly alkaline glycine brine solution, selectively leaching valuable metals Zn, Pb and Cd in the zinc-containing smoke dust of the iron and steel plant by use of difference between cooperation capabilities of metal ions in the zinc-containing smoke dust and ligand glycine ions; reducing and purifying the leachate by use of zinc powder so as to obtain lead-cadmium enriching residue; and directly performing electrodeposition on the purified solution so as to obtain electric zinc. The method is mild in used system, low in equipment anticorrosion requirement and low in toxic and side effects on a human body and environment, and belongs to a clean metallurgical technology; a used accessory ingredient aqueous solution can be regenerated and recycled in a treating process, so that the treatment cost is low; and the method is capable of treating the zinc-containing smoke dust with high iron content, realizing deep separation of iron and zinc, effectively removing toxic heavy metal elements Zn, Pb and Cd in the zinc-containing smoke dust of the iron and steel plant, preparing the electric zinc, effectively enriching valuable metals lead and cadmium and realizing comprehensive utilization of resources.