The present invention relates to the field of pharmaceutical synthesis, and disclosed thereby is a method for synthesizing linaclotide. The method uses a solid phase one-step cyclization method to prepare linaclotide, and a linaclotide linear resin directly undergoes one-step cyclization by using a N-X succinimide solution oxidation system without cracking to obtain a linaclotide resin, the resin then being cracked, purified and lyophilized to obtain linaclotide. The N-X succinimide is one from among N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide, and N-hydroxythiosuccinimide. The method has the following advantages : 1. using solid phase cyclization, and first of all having a false dilution effect, preventing the repeated folding of peptide chains, and being capable of performing a cyclization reaction at a high concentration, which may greatly increase production efficiency; second, the linear peptide resin not being cracked before cyclization, thus preventing the production of a large amount of impurities, and improving the efficiency of linaclotide cyclization. 2. one-step cyclization being carried out by using N-X succinimide, which may avoid the multi-step purification of an intermediate, thus reducing the components of the intermediate purification step, and improving the total yield of linaclotide. 3. using specific amino acid side chain protecting groups, and a pair of disulfide bonds being positioned during cyclization, thus reducing the generation of mismatched by-products, improving the purity of linaclotide, greatly increasing production efficiency, and reducing manufacturing costs.