Abstract: Telomeres are closely related to human aging and tumors. Telomeres are special structures at the ends of eukaryotic chromosomes, which can prevent degradation, fusion, and rearrangement of the ends of chromosomes, and play an important role in maintaining the stability and integrity of the genome. In an individual's lifetime, the telomere length of somatic cells gradually shortens with time, but tumor cells have stable telomere lengths and permanent biochemical characteristics due to the reactivation of telomerase. Shortening of telomere length often increases the risk of aging-related diseases, while telomere length extension increases the risk of tumors. In recent years, a large number of studies have confirmed that the change in telomere length affects the development of tumors and that telomere length can predict tumor risk, showing the significance of telomere length in accurate diagnosis and treatment. This article reviews the role of telomere length in cell carcinogenesis and tumor risk prediction.