Telomere is a specific ribonucleoprotein complex composed of repeats of sequence TTAGGG, and located at the eukaryotic chromosometerminus. While it plays an important role in maintenance of telomere structural stability, telomerase is also involved in the regulation of telomerase activity. Telomerase activity is due to transcriptional repression of the catalytic subunit hTERT in most tissues prior to birth and is reactivated by upregulation of hTERT expression in over 90% of cancer cells. The mechanisms involved in telomerase regulation are still far from being fully established. Telomerase activity is subject to multiple levels of control and may be regulated by different factors in different cellular contexts. In this paper, some factors such as cell differentiation, molecular regulation, cell cycle and actuality of telomerase was reviewed.