Abstract: The present invention relates to a method for preparing GLP-1 receptor agonist, specifically relates to an industrialized method for preparing a GLP-1 receptor agonist (S)-2-(3S,8S)-3-(4-(3,4-dichlorobenzyloxy)phenyl-7-((S)-1-phenylpropyl)-2,3,6,7,8,9-hexahydro-[1,4]-dioxino[2,3-g]isoquinolin-8-ylformylamino)-3-(4-(2,3-dimethylpyridin-4-yl)phenyl)propanoic acid dihydrochloride (compound I). The method utilizes compound 1 as the starting material, which undergoes nucleophilic addition, hydrolysis, reduction ammoniation, cyclization, amide condensation, hydrolysis, and salt forming reaction to give compound I. The method for preparing compound I has a total yield of more than 35%, with purity of compound I more than 98%.