The present disclosure relates to a composition for treating and preventing an ischemic injury. More particularly, it relates to a composition containing a peptide derived from a telomerase, which is effective in treating and preventing an ischemic injury. The peptide according to the present disclosure, a peptide having 80% or more sequence identity with the amino acid sequence of the peptide or a peptide which is a fragment thereof, has a superior effect of treating and preventing an ischemic injury. Accordingly, a composition containing the peptide may be effectively used for an ischemic injury, particularly for an ischemic-reperfusion injury.