The invention provides a copper smelting method. The copper smelting method is conducted in a copper smelting device provided with an inner cavity. The inner cavity comprises a smelting area, a dilution area and a sedimentation area. The dilution area and the smelting area are separated through a first separation wall, and the dilution area communicates with the smelting area through a smelting slag channel. The sedimentation area and the dilution area are separated through a second separation wall. The sedimentation area is located on the side, away from the smelting area, of the dilution area, and the sedimentation area communicates with the dilution area through a dilution slag channel. The copper smelting method comprises the following steps that copper concentrates are smelted in thesmelting area, and first copper sulphate and smelting slag are obtained; the smelting slag is subjected to dilution treatment in the dilution area, and second copper sulphate and dilution slag are obtained; and the second copper sulphate and the dilution slag are subjected to sedimentation separation in the sedimentation area. Through the copper smelting method, copper smelting, dilution and sedimentation separation are concentrated in a furnace, waste slag with a very low copper content is obtained while high-grade copper sulphate is produced, the number of procedures is small, and the technological process is shortened greatly.