The invention relates to a carbetocin synthesis method. The carbetocin synthesis method solves the problem that the prior art has a high cost, low purity and more impurities. The carbetocin synthesis method comprises the following steps of orderly coupling seven amino acids to wang resin, wherein the coupled amino acids orderly comprise Fmoc-Leu-OH, Fmoc-Pro-OH, Fmoc-Cys(Trt)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Ile-OH and Fmoc-Tyr(Me)-OH, removing a protective group Fmoc, connecting 4-chlorobutyric acid, carrying out cracking to obtain an acylated carbetocin seven-peptide linear peptide, carrying out liquid cyclizing under alkaline conditions to obtain a carbetocin seven-peptide crude cyclopeptide, carrying out purification and freeze-drying on the crude cyclopeptide to obtain a carbetocin seven-peptide fine cyclopeptide, and coupling the fragment of the carbetocin seven-peptide fine cyclopeptide subjected to purification and freeze-drying and H-Gly-NH2.HCl to obtain carbetocin. The invention provides the carbetocin synthesis method having a low cost and a high yield and suitable for large-scale production.