The invention discloses a method and equipment for depleting the furnace slag of an electric melting furnace of a side-blowing melting pool. The method comprises the following steps of: putting molten slag produced in the nickel melting process or blown slag produced in the process of blowing low-nickel sulfonium into high-nickel sulfonium into a reduction zone of the electric melting furnace of the side-blowing melting pool, controlling the temperature of the furnace to be in a range of 1300 DEG C-1400 DEG C, and injecting a reducing agent into an inclined inserting port of a spraying gun of the electric furnace. By adopting the method in the invention, slag-type optimization of the furnace slag containing nickel, transformation from nickel chemically dissolving in the slag into sulfonium I and separation of the slag and the sulfonium are finished in the electric melting furnace of the side-blowing melting pool. The invention has the advantages that reducing and slag making reaction of magnetic iron oxide, sulfonium making reaction and slag-sulfonium settlement and separation are finished at different zones in one side-blowing electric furnace; the nickel content in the waste slag is low; and the foaming of the furnace slag is avoided and the operation process is smooth and safe.