Wave　propagation　and　band　gap　(BG)　characteristics　of　deploying　long　pipes　conveying　fluid　are　investigated　based　on　a　phononic　crystal　(PC)　pipe　model.　The　dispersion　relation　of　the　corresponding　time-variant　uniform　pipe　system　is　first　derived　in　terms　of　the　traveling　wave　feature　of　axially　moving　structures.　Basic　wave　properties,　such　as　the　propagating　and　evanescent　waves　and　the　phase　velocity　and　group　velocity　of　propagating　waves,　are　discussed　to　demonstrate　the　great　effects　of　the　flow　velocity　and　deploying　speed.　The　band　structures　of　deploying　pipe　conveying　fluid　with　periodic　varying　parameters　are　then　investigated　based　on　the　Bragg　scattering　mechanism　and　treated　by　the　transfer　matrix　method.　A　complex　propagation　constant　is　used　to　measure　the　band　distribution.　The　fluid-structure　interaction,　deploying　motion　and　component　geometry　are　all　found　to　have　significant　effects　on　the　location　and　width　of　the　BGs　of　the　pipe.　The　deploying　speed　and　flow　velocity　mainly　influence　the　lower　BGs　while　the　component　geometry　acts　much　on　the　higher　ones.　(C)　2019　Elsevier　Inc.　All　rights　reserved.