Abstract: Circular RNA is a non-coding RNA that acts as a sponge for RNA, regulates cleavage and transcription, translates proteins and interacts with RNA-binding proteins. In recent years, studies have found that the abnormal expression of circular RNA in tumor tissues is closely related to the occurrence, development and prognosis of lung cancer and it is expected to be a biomarker for the diagnosis, treatment and prognosis of lung cancer. Therefore, this paper reviews the research progress of circular RNA as a biomarker of lung cancer.