The invention provides a retarder used in a refractory material, which is prepared by the following steps: weighing polyester polyol, silsesquioxane and diisocyanate according to the ratio, adding thepolyester polyol, the silsesquioxane and solvent N-methylpyrrolidone into a reaction container, fully stirring, heating, adding the diisocyanate, adding a catalyst, keeping the temperature and continuously stirring after the catalyst is added, and then keeping the temperature after heating to prepare a prepolymer of which the end group is -NCO; cooling, adding sodium hydrogen sulfite into the reaction container, continuously stirring, keeping the temperature, finally adding water into the reaction container, and continuously stirring, so as to obtain the retarder for the refractory material.The retarder can adjust the setting time of the refractory castable, avoids premature setting of the castable, has good operability, and can greatly reduce the construction energy consumption. Meanwhile, the retarder for the refractory material can also be used as a dispersing agent to improve the flowability of the refractory castable and reduce the consistency.