The invention relates to a technique of renewable desulfurization, and the application thereof. The technique comprises the steps of the washing and cooling of desulfurated flue gas, the absorption and desorption of SO2 and heat energy supply during a desorption process and is characterized in that: at least part of heat energy required during the desorption process is supplied by the physical sensible heat carried by the flue gas to be desulfurated so as to solve the problems that during the desulfurization process, on the one hand, a great amount of steam is consumed for heating, and on the other hand flue gas needs to be cooled quickly at very low temperature in a pre-washing tower, thus leading to dual energy consumption. The invention also relates to the application of the technique of the renewable desulfurization, for example, flue gas desulfurization applicable to a sintering system of a steel plant, the flue gas desulfurization applicable to ironmaking blast furnace gas and the like. The technique and the application have the advantages of saving energy and water as much as possible and reducing heat pollution to the environment while saving energy.