In the long-term evolution process, insects have formed a unique intestinal defense system. The combination of physical barrier and the immune system resists invasive microbes. Alike most metazoans, the guts of insects are in permanent contact with the microbial realm that includes beneficial symbionts, food-borne microbes and life-threatening pathogens. Thus, gut epithelium can tolerate a certain amount of commensal microbes proliferation for the beneficial gut-microbe interactions, accompanied by the proficient elimination of detrimental microbes. Based on the function of Duox-ROS system and immune deficiency pathway in the intestinal immune response, these immune systems are involved in the regulation of gut microbiota homeostasis. In this article, we reviewed recent advances in insect intestinal defense mechanisms, combined with the intestinal immune signaling pathways and the regulation mechanism of intestinal immune system on the gut microbiota homeostasis.