The invention relates to the steelmaking technical field of the metallurgical industry, and in particular relates to a method for producing low-sulfur steel through the converter duplex technology. The production method comprises the following steps: (1) adding a desulfurizer in molten iron slagging iron slag to perform knotted reactor (KR) desulphurization treatment, skimming the desulfurized molten iron, and adding in a dephophorization furnace; (2) adding scrap steel and slag materials in the dephophorization furnace, blowing, and adding semisteel in a decarbonization furnace after the treatment; and (3) adding the slag materials in the decarbonization furnace, and blowing to ensure that S content in the molten steel is less than 0.005% after blowing. The method does not adopt low-frequency (LF) furnace refining to desulfurize; a converter can be directly used to stably produce the molten steel of which S content is less than 0.005%, thus better matching the production rhythm of continuous casting; for the production of the low-sulfur steel, S content is controlled to be less than 0.005% by the converter, thus the carburization and nitrogen increasing of molten steel caused by LF desulfurization can be avoided; and the total consumption amount of lime in the converter is less than 35kg/t and the total slag quantity is less than 70kg/t.