An　integral　3D　numerical　model　based　on　the　structural　characteristics　of　the　emitter　with　arc　labyrinth　channels　was　constructed　to　simulate　the　relationship　between　flow　rates　and　pressure　heads　as　well　as　the　flow　field　distribution　in　the　small　channels　by　computational　fluid　dynamics　(CFD).　Meanwhile,　the　emitter　prototypes　fabricated　by　stereolithography　technology　were　used　in　the　flow　rate　experiments.　The　calculation　results　obtained　revealed　turbulence　model　can　supply　a　better　agreement　with　the　experimental　data　than　laminar　flow　model　under　pressure　ranges　of　40-160　kPa.　Most　pressure　losses　are　occurred　in　labyrinth　channels　and　the　losses　within　each　arc　unit　are　constants　under　different　inlet　conditions.　In　addition,　laser-Doppler　velocimetry　(LDV)　was　employed　to　measure　the　flow　fields　of　the　magnified　model　with　a　magnifying　scale　of　15:1　according　to　the　channel　structure　of　the　emitter,　and　the　measured　velocity　distribution　in　the　cross-section　is　in　good　agreement　with　calculation　results.　It　was　found　that　reversed　flow　happened　near　the　upper　fringe　of　the　flow　path,　and　that　in　the　longitudinal　symmetric　plane　mainstream　velocity　regions　and　low　velocity　regions　could　be　observed　clearly.　The　vortexes　of　different　sizes　were　developed　in　low　velocity　regions,　which　may　be　one　of　the　reasons　leading　to　channel　clogging.　(c)　2007　Elsevier　B.V　All　rights　reserved.