A series of 3-(2-cinnamamidoethylsulfonyl)thiazolidine-4-carboxylate derivatives were designed, synthesized, and evaluated for their angiotensin converting enzyme (ACE) inhibitory activity. Their structures were verified by 1H NMR, 13C NMR, IR, and MS. All these compounds exhibited inhibitory activity against ACE with IC50 value of 3-9 mM, and 10g showed the most potent activity.