Abstract: The effect of CaO/MgO ratios on the efficiency of sulfur fixation was studied under the different combustion temperatures and the quantities of the sulfur-fixing agents. The results showed that the efficiency of sulfur fixation is different under the same temperature but different CaO/MgO ratio;and the best CaO/MgO ratio is also different under the different temperature and varies with the temperature.The quantity of the CaO increases and the MgO decreases when the temperature goes up.The best sulfur-fixing temperature and the quantity of the sulfur-fixing agents have nothing to do with the relation between the CaO/MgO ratio and the rate sulfur capture.