Telomeres are at the ends of eukaryotes chromosomes, protect chromosomes integrity in replication. Telomeres shorten with mitosis, telomerase prolong telomeres in cells, such as embryonic stem cell. There are two protein complexes binding on telomeres: shelterin complex and CST complex. Telomerase synthesize telomeres use its RNA components. Both the telomere binding proteins and the telomerase play great role in maintaining telomere length and stability. Although telomere sequences are similar in different species, telomere and telomerase functions are not related in physiological and/ or pathological conditions. Here we review the composition and function of telomere binding protein and telomerase, to understand the biological function of telomere and provide scientific basis for the treatment of telomere dysfunction.