The invention relates to the technical field of steel smelting, in particular to an ultra-low carbon steel slag oxidability and adsorbability control method. The method comprises the steps that duringconverter smelting, slag-stopping tapping is adopted, the tapping time is controlled to range from 4 minutes to 6 minutes, and the slag layer thickness is controlled to be smaller than or equal to 80mm; in the converter tapping process, lime and fluorite are added; in the converter tapping process, online bottom argon blowing is carried out, after converter tapping is finished, bottom blowing isstopped; bottom and after blowing is stopped the slag face is calm, first high calcium aluminum slag balls are added into the slag face; after first high calcium aluminum slag ball charging is finished, steel ladle capping is carried out, and a steel ladle is subject to RH refining; in the RH refining process, after decarburization is finished, a slag sample is taken out, slag components and content are analyzed, and the molten steel dissolved oxygen content is measured; after RH refining is finished, second high calcium aluminum slag balls and lime or bauxite are added to the slag face, andsteel ladle capping is carried out. According to the ultra-low carbon steel slag oxidability and adsorbability control method, the ultra-low carbon steel slag oxidability is reduced and the ultra-lowcarbon steel slag adsorbability is improved.