The present invention relates to a method of preparing a peptide comprising the amino acid sequence His-Gly-Asp-Gly-Ser-Phe-Ser-Asp-Glu-Met-Asn-Thr-Ile-Leu-Asp-Asn-Leu-Ala-Ala-Arg-Asp-Phe-Ile-Asn-Trp-Leu-Ile-Gln-Thr-Lys-Ile-Thr-Asp (SEQ ID NO:1). In particular, the method comprises the steps of providing a first peptide fragment having a first protection group, which peptide fragment is conjugated to a support； providing a second peptide fragment having a second protection group； removing the first protection group from the first peptide fragment； and coupling the second peptide fragment to the N-terminally deprotected, support-conjugated first peptide fragment. The present invention further relates to a method of preparing a pharmaceutical composition containing said peptide.
