Sulfonamide is a special type of compound known for its versatile biological activity. The synthesis of these compounds has attracted manyattention of pharmaceutical chemists and organic chemists. Sulfonylation was accomplished between chloromethanesulfonyl chloride and aromatic primary amine in the presence of pyridine in this article. The reaction conditions such as catalyst, solvent, molar ratio of the material and reaction temperature were investigated.The results indicated that the optimized reaction conditions were determined as follows: n (amine) : n (chloromethanesulfonyl chloride) = 1 :1.3, pyridine as catalyst, dichloromethane as solvent , reaction at 0 ℃ to room temperature for 4~8 h. Under the optimized reaction conditions, a series of chloromethyl sulfonamide was obtained in 42%~95% yields. The structure of newly synthesized compounds was determined by IR, 1HNMR and 13CNMR.