Abstract: The present invention discloses an inactive telomerase, which is a double mutant telomerase having double mutation sites Y707F and D868A. The present invention also discloses an adenovirus-inactive telomerase and an artificial mRNA-inactive telomerase having double mutation sites, and use thereof in the treatment of diseases associated with non-dividing cell telomere shortening. The present invention is capable of inhibiting the activity of telomerase TERT in non-dividing cells to form an inactive telomerase CI-TERT and simultaneously preventing the telomerase from leaving the nucleus. By such configuration, the telomerase can be kept in the nucleus to protect the telomeric ends from shortening and prevent telomerase from causing telomere lengthening to the extent of cell carcinogenesis, thus reducing the risk of carcinogenesis and keeping the telomerase in the nucleus to protect the telomeric ends and inhibiting the deterioration of the disease caused by telomere shortening.