The invention discloses a method for producing duplex stainless steel. The method comprises the steps that 1, molten iron is desiliconized and dephosphorized, alloy is molten in an intermediate frequency furnace, the treated molten iron and the molten alloy are mixed into a refining furnace for decarbonization, reduction, nitrogen discharging and deep desulfurization, and after the mass fraction of components of molten steel meets the preset requirement, the molten steel is tapped to a steel ladle; 2, the refining furnace is pulled in, argon blowing is carried out after the refining furnace is pulled in, after electrochemical residues are fed, a pure calcium line is added, lime and fluorite are added, power is transmitted to heat the molten steel, aluminum particles are added according to the residue color condition to adjust the residue color to be white, and after the mass fraction of the molten steel meets the preset requirement, argon flow is adjusted, ferroboron is added, and steel tapping is carried out soft blowing; 3, after the molten steel stands still, pouring is carried out, and duplex stainless steel blanks are produced.