Abstract: Extracting process of potassium fertilizer with potassium feldspar-phosphogypsum-coke system is a feasible industrialization route to utilize insoluble potassium resources, in which the reaction process of coke and phosphogypsum is the key to raise the potassium extraction rate. In this paper, the influence of the ratio of activated carbon to phosphogypsum on potassium extraction rate is studied under N₂ or CO₂ atmosphere. Two different roasting temperature systems, heating up with the furnace and feeding at constant temperature, are used to compare the potassium extraction rate and roasted products under different atmospheres. The results showed that as the content of activated carbon in the system increased, the potassium extraction rate increased first and then decreased. Under N₂ atmosphere, the rate of potassium extraction in samples that heating with constant temperature is greater than that of samples heating with the furnace. In CO₂ atmosphere, when the ratio of activated carbon to phosphogypsum is less than 3:6, the potassium extraction rate of samples heating with constant temperature is greater than that of samples heating with the furnace; when the ratio of activated carbon to phosphogypsum is greater than 3∶6, the potassium extraction rate of samples heating with the furnace is greater than that of samples heating with constant temperature.