Novel insecticide synergist and application thereof

The invention relates to an insecticide synergist belonging to the technical field of pesticides. The control effect of an insecticide is improved by mixing methimazole and analogues, such as carbimazole, of the methimazole with the insecticide. When the methimazole and the insecticide are mixed, the toxicity of the insecticide to the pest population resistance to the insecticide can be remarkably improved, the control effect of the insecticide is greatly improved, and the consumption of the insecticide is reduced; and especially, the insecticide synergist has an important value for treating the pest population resistance to the insecticide. Meanwhile, new application of the methimazole and the carbimazole as drugs for treating hyperthyreosis is developed.