Abstract In this thesis, the thymosin α1 has been synthesized by a solid-phase method. Using the base-labile Fmoc group to protect the α-amino acid, and present a strategy for the synthesis of a thymosin α1. Then a suitable synthesis method is determinedie, that is using preformed symmetrical anhydrides(PSA)in the first 9 synthesis steps, using DCC-HOBt chemistry coupling in the next 18 steps. The result shows that the yield of the coupling synthesis of each step is over 96.2%, most of them are over 99%. Meanwhile, technology conditions of synthesis were studied. The purification of our product (the content of Tα1) is 46.52%, the yield of it is 37.81%.