Numerous　methods　have　been　developed　for　peptide　synthesis　due　to　their　great　potential　in　drug　discovery.　However,　the　technique　for　tryptophan-cysteine　conjugation　is　still　underexplored.　Herein,　we　present　a　TMSBr-promoted　ligation　of　tryptophan　and　cysteine　under　mild　conditions　by　using　a　sulfonate-modified　cysteine　substrate.　This　protocol　features　a　broad　scope　and　high　site　selectivity　and　is　applicable　for　synthesis　of　cyclic　peptide.　Preliminary　mechanistic　studies　reveal　that　the　reaction　proceeds　via　a　radical　process.