Abstract: Based on the reported IDO1 inhibitor U - 3i , 11 phenylsulfonamide derivatives were designed and synthesized by adopting bioisosterism and molecular docking technology. The inhibitory activities of the target compounds against IDO1 were determined by the HeLa cell-based kynurenine assay. The results demonstrated that most compounds showed different degrees of inhibitory effects on IDO1. Among them, compounds 3b and 3e displayed the most potent activity and could reverse IDO1-mediated immune suppression, which might be worth of further investigation.