Innate lymphoid cells have recently been identified to be a cell population that has morphology typical of lymphocytes but lacks rearranged antigen receptors. It can be classified into RORγt innate lymphoid cell, type 2 innate lymphoid cells and natual killer cells. Among them, type 2 innate lymphoid cells plays an important role in type 2 immunity by releasing type 2 cytokines, such as interleukin-5 and interleukin- 13, and makes a match for Th2 cell of the adaptive immune system. Type 2 innate lymphoid cells responses are initiated by interleukin-25 and interleukin-33, which are produced by several cell types, such as epithelial cells, tissue macrophages and dendritic cells. These cytokines strongly activate type 2 innate lymphoid cells, leading to the production of type 2 cytokines, including, interleukin-5 and interleukin- 13. In this review, we will discuss the characteristics and development of type 2 innate lymphoid cells and the role of type 2 innate lymphoid cells in allergic diseases in detail.