ILCs (innate lymphoid cells), new members of innate immunity, have been discovered over last ten years. According to transcription factors they express and cytokines they secret, ILCs can be divided into different groups. Common lymphoid progenitor cells (CLPs) in bone marrow can differentiate into α-lymphoid progenitors (αLP), early innate lymphoid progenitor (EILP), common helper ILC progenitor (CHILP), helper ILC progenitor (ILCP) gradually and finally generate mature ILCs. ILCs receive signal from environment through interacting with nerve cells, epithelial cells, stromal cells, adaptive immune cells, myeloid cells, microbiota and can participate in a lot of biological processes such as pathogen infection, chronic inflammation disease, organogenesis, tissue repair, cancer, metabolism and circadian rhythm. In some cases, ILCs play a redundant role which tell us ILCs may be selected as new therapeutic targets. In this review, we summarize recent research progress on innate lymphoid cells including their classification, development and differentiation, interaction with other cells, biological processes, therapeutic strategy and future prospects.