Abstract: Insect innate immunity is the first defense way that fights off microbial infections, and the immune deficiency (IMD) signaling pathway is the most important way that controls the gene expression of most of the antimicrobial peptides in normal immune regulation of insects. In this article, we review current literatures on the insect IMD pathway, and sum up the positive regulation mechanism of IMD signaling pathway including peptidoglycan- recognition proteins and action way, Imd, dFADD and Dredd signal complex formation and regulation pathway, Relish activation and other positive adjustment factors. We also systematically summarize the action modes of negative regulators, such as negative regulation mechanism of PGRPs, ubiquitin and nuclear negative regulators involved in the negative regulation of Imd signaling pathway. This article provides a reference for further understanding the molecular mechanism of the insect immune response pathway.