In this study, potassium vapor was prepared by using potassium carbonate (K2CO3) and activated carbon (C) reagents to simulate the actual situation of adsorbing potassium vapor from the sinter in the blast furnace. The potassium-rich sinter was characterized by X-ray diffraction (XRD), flame atomic absorption spectrometry (FAAS), and scanning electron microscopy (SEM-EDS). The effects of potassium vapor content on the enrichment ratio, adsorption rate, and low-temperature reduction degradation index (RDI+3.15mm) of sinter have been studied. The results show that with the increase of potassium vapor content, the enrichment ratio of potassium in the sinter increases, and the adsorption rate of potassium in the sinter increases first and then decreases, which was opposite to the trend of the low-temperature reductive degradation index of the sinter. When the potassium vapor content was increased by 50 times, the enrichment ratio and low-temperature reduction powder of the sinter are the highest, which were 2576% and 85.3%, respectively, and the adsorption rate of the sinter was the lowest, which is 51.5%. Meanwhile, potassium vapor changes from physical adsorption K2CO3 to chemical adsorption KFeO2 as the potassium vapor content increases. In addition, the transformation of the occurrence form of potassium vapor in the sinter during the rising process has also been clarified.