3-iodo-N1-(2-methyl-4-(perfluoropropan-2-yl)-N2-(2-methyl-1-(methylsulfinyl)propan-2-yl)phenyl)phthalamide was synthesized from isobenzofuran-1,3-dione via amidation, oxidization, iodination. The effects of materials' mole ratio, the amount of catalyst, reaction temperature and time on the yield of product were studied. In the improved process, after 4 steps, the total yield could reach 61.1%, and the purity of product was 96.5%. Structures of all intermediates and target product were characterized by 1HNMR and ESI-MS. The recovery and reuse of Palladium carbon could reduce the economic costs. This synthetic route is characterized by cost-effectiveness, simple operation and high yield , which are very promising in industrialization.