The invention discloses a synthetic method for a II-type diabetes medicine glimepiride by using triphosgene. After N-4-[2-(3-ethyl-4-methyl-2-oxo-3-pyrroline-1-formamido)ethyl]-benzsulfamide and trans-4-methylcylohexylamine in a solvent are reacted under existence of an acid-binding agent by adding dropwise slowly the triphosgene and controlling the temperature at a certain temperature, a target product is prepared after post-treatment. The method has simple technology, easy operation and high product yield. Solid phosgene (namely the triphosgene) is safer than phosgene in using, and is convenient to operate.