Intestinal barrier act as the crucial defender against pathogen invasion, and is indispensable in maintaining tissue homeostasis both locally and systemically. Severe disease can lead to impaired intestinal barrier. In addition to cause a variety of gastrointestinal diseases, intestinal barrier damage can also worsen the disease progression in critically ill patients. Innate lymphoid cells (ILCs) is a group of newly defined innate immune cells which have some characteristics as adaptive immune cells. Group 3 innate lymphoid cells (ILC3), which mainly reside at gut associate mucosal tissue, have been reported to play a critical role in maintaining intestinal barrier function. After a brief introduction about its origination and classification, we will focus on function of ILC3 physiologically and pathologically, and provide a new theoretical basis for maintaining intestinal barrier function under pathological conditions in this review.