The present invention relates to a method for preparing branched polypeptides. The method comprises the following steps: a. selecting the first amino acid at the C-terminal of a target peptide, the carboxyl-group of the first amino acid is connected with a solid carrier by a covalent bond to obtain the amino-acid resin when the amino-group is protected b. starting from the first amino acid which is connected to the solid carrier in step a, the successively connection of each amino acid of the target peptide is achieved by repeating the following three steps: ①deprotection of N-terminal, then washing and filtering ②with the amino-groups and the side chains being protected, the amino acid is connected with the adjacent amino acid through a peptide bond which is formed by the condensation and acylation of the amino-group and the carboxyl-group of the two adjacent amino acids ③washing and filtering again the branching part is lysine which contains two amino-groups c. by cleavage and post-processing, the target peptide is separated from the amino-acid resin and all the protecting groups for side chains, and the crude target peptide is obtained. The invention is conducive to the control and amplification of process. The source of raw materials is stable, and the method of post-processing is simple.La présente invention concerne un procédé de synthèse de polypeptides ramifiés. Ledit procédé comprend les étapes suivantes : a. en choisissant le premier acide aminé à lextrémité C dun peptide cible, le groupement carboxyle du premier acide aminé est connecté à un vecteur solide par une liaison covalente pour obtenir la résine dacides aminés lorsque le groupement amino est protégé b. en partant du premier acide aminé relié au vecteur solide dans létape a, chaque acide aminé du peptide cible est successivement connecté en répétant les trois étapes suivantes : ① déprotection de lextrémité N, puis lavage et filtration ② Les groupements amino et la chaîne latérale étant protégés,
