We　propose　an　efficient　scheme　for　deterministic　generating　atom　Greenberger-Horne-Zeilinger　(GHZ)　states　in　separate　coupled　cavities　connected　by　optical　fibers　based　on　quantum　Zeno　dynamics　only　by　one-step　manipulation.　Firstly,　we　discuss　the　generation　of　three-atom　GHZ　states　in　separate　cavities.　Then,　the　scheme　is　directly　generalized　to　-atom　case　without　increasing　new　operations　in　experiment.　The　influence　of　decoherence　induced　by　atomic　spontaneous　emission　and　the　fibers　and　cavities　losses　is　discussed　by　numerical　calculation.　The　results　show　that　the　scheme　is　insensitive　to　the　optical　fibers　decay　due　to　a　tiny　excitation　probability　of　the　optical　fibers　during　the　operation.