Telomeres consisting of tandem repetitive sequence,which cap the ends of chromosomes are crucial in maintaining chromosomal integreity and genome stability. Many methods can be used to quantitatively or relative quantitatively measure telomere length. Telomere length can reflect the degree of celluaraging and health status of the organism. The telomerase reverse transcriptase can lengthen telomere by synthesising telomere with its own template sequence. Telomere length and telomerase have been implicated with the development of cancer. Genetic and environmental factors can influence telomere length. Telomere length has the potential to be a biomarker to indicate the risk of cancer development and progression. To date,a series of studies have been conducted to evaluate the relationship between telomere length and cancer risk,and found a different role in different tumors. Therefore,we reviewed and summarized the progression in this field around the world.