The invention discloses an exothermic insulating riser sleeve and a preparation method thereof and aims to solve the problems of bad heat insulation, insufficient heating and single effect in a conventional exothermic insulating riser sleeve. According to the formula, the exothermic insulating riser sleeve is prepared from quartz sand, vermiculite, potassium nitrate, calcium chloride, iron sesquioxide powder, graphite powder, aluminum powder, magnesium powder and modified sodium silicate. The method comprises the following steps: (1) weighing raw materials; (2) preparing a mixed wet material; and (3) filling the mixed wet material into a mold, pre-tightening while filling the wet material, performing compression molding, and demolding, thus finishing the operations. According to the formula of the exothermic insulating riser sleeve, the content of an exothermic agent is increased, the exothermic agent has the advantages of rapid heating, and a heating effect is improved. Moreover, the vermiculite serves as a thermal insulation material, is long in thermal insulation time and has a good thermal insulation effect, so that the molten iron feeding ratio in a riser is improved under the combined action of rapid heating and long thermal insulation.