The present invention relates to a peptide for treating a demyelinating disease and a use thereof. More specifically, it was confirmed that the trimeric peptide according to the present invention suppresses demyelination and enhances myelination in a chronic inflammatory demyelinating polyneuropathy (CIDP) animal model and an acquired peripheral nerve injury animal model, and improves nerve damage and symptoms caused by demyelination. Accordingly, the peptide of the present invention can be usefully employed as an active ingredient in a composition for the prevention or treatment of demyelinating diseases, including CIDP.