The invention provides a method for increasing the sulphur content of welding wire steel. During smelting of a converter, high-sulphur-iron ores are used as iron-containing cold materials for replacing low-sulphur iron-containing cold materials, the sulphur content of the high-sulphur-iron ores is more than 0.85wt%, and slagging materials lime and magnesium balls are replenished. According to the method provided by the invention, the technical principle of low sulphur content proportion of steel slag-molten steel under an oxidizing atmosphere of the converter is utilized, the high-sulphur-iron ores with a sulphur content of more than 0.85wt% are used as the iron-containing cold materials for replacing the low-sulphur iron-containing cold materials during a smelting process, the sulphur content of the refined molten steel is increased by increasing the sulphur content in a smelting system of the converter and increasing the sulphur content of steel tapping of the converter on the premise of meeting the smelting heat balance of the converter, sulphur increasing of a sulphur line or sulphur-iron is replaced, and the sulphur content is stably controlled. Experimental results indicate that the method for increasing the sulphur content of the welding wire steel is capable of meeting the smelting heat balance of the converter, and moreover, the sulphur content of the refined molten steel is basically controlled to be 0.009-0.017wt%, so that the requirements of finished product control are met.