Web　service　choreography　describes　global　models　of　service　interactions　among　a　set　of　participants.　For　an　interaction　to　be　executed,　the　participants　must　know　the　required　channel(s)　used　in　the　interaction,　otherwise　the　execution　will　get　stuck.　Since　channels　are　composed　dynamically,　the　initial　channel　set　of　each　participant　is　often　insufficient　to　meet　the　requirements.　It　is　the　responsibility　of　the　participants　to　pass　required　channels　owned　(known)　by　one　to　others.　Since　service　choreography　may　involve　many　participants　and　complex　channel　constraints,　it　is　hard　for　designers　to　specify　channel　passing　in　a　choreography　exactly　as　required.　We　address　the　problem　of　checking　whether　a　service　choreography　lacks　channels　or　has　redundant　channels,　and　how　to　automatically　generate　channel　passing　based　on　interaction　flows　of　the　service　choreography　in　the　case　of　channel　absence.　Concretely,　we　propose　a　simple　language　Chor　(c)　,　a　channel　interaction　sub-language　for　modeling　the　channel　passing　aspect　of　service　choreography.　Based　on　the　formal　operational　semantics　of　Chor　(c)　,　the　algorithms　for　static　checking　of　service　choreography　and　generating　channel　passing　are　also　studied,　and　the　complexity　results　of　algorithms　are　discussed.　Moreover,　some　illustrated　service　choreography　examples　are　presented　to　show　how　to　formalize　and　analyze　service　choreography　with　channel　passing　in　Chor(c)　.