With the increasing understanding of mesenchymal stem cells (MSCs), their potential in tissue engineering and regenerative medicine has attracted more attention. However, some important problems need to be solved before clinical application, such as low amplification efficiency, inconsistent cell product quality, and unsatisfactory survival rate at the receptor site. Telomeres act as a clock, and they shorten when cells divide. The main mechanism for reversing telomere length is telomerase. Furthermore, telomerase is involved in antioxidation, antiapoptosis, immunological modulation, and other noncanonical processes in addition to proliferation-related tasks. Therefore, it is necessary to understand the telomere biology and telomerase of MSCs to improve their proliferation, performance stability, and antiscavenging ability. This review summarizes the progress of telomerase biological function and mechanism in MSCs, and discusses the current situation and deficiency of telomerase-related application in MSCs.