A new independent subtype CD4+ T cell which massively secreted interleukin-17 (IL-17) was found at the beginning of the 21st century, and thus it was named as T helper cell 17 (Th17 cell). With the progress of the research in recent years, Th17 cells were found to be widely involved in a variety of the human diseases such as autoimmune diseases, infections and tumors through secretion of IL-17. The relationship between Th17 cells, IL-17 and the occurrence, development and prognosis of lung cancer was reviewed.