The invention discloses a method for restraining fusarium graminearum in food grains through chlorine dioxide, and belongs to the technical field of food safety. The method comprises the following steps of pouring polluted food grain raw materials into a light-resistant container, adding water, performing soaking and incubation for some time, then charging ClO2, performing a reaction, and enablingreaction tail gas including the ClO2 to be absorbed with a sodium thiosulfate solution through a pipeline, so that pollution and damage are avoided. According to the method disclosed by the invention, the fusarium graminearum in the polluted food grains is effectively restrained with ClO2 water, the method is simple, the fusarium graminearum can be safely and effectively restrained, further pollution caused by the fusarium graminearum after the food grains are harvested is avoided, and the restraint ratio can reach 90% or above.