Distilled　water　and　nitrogen　gas　used　as　the　working　fluids　flow　through　the　stainless　steel　microtube　with　inner　diameter　168　mu　m　outer　diameter　406　mu　m.　Using　the　Joule　heating,　the　wall　temperature　field　photos　of　the　microtube　is　acquired　by　employing　an　IR　camera　and　the　temperature　and　the　volume　flow　rate　of　the　inlet　and　the　outlet　of　microtube　are　measured.　A　correlation　between　the　axial　wall　heat　conduction　and　the　convective　heat　transfer　is　obtained　by　theoretical　analysis　based　on　the　experimental　results.　The　investigative　results　clearly　show　that　the　axial　heat　conduction　can　reduce　the　convective　heat　transfer　in　the　stainless　steel　microtube　and　the　decrement　may　reach　2%　compared　to　the　convective　heat　transfer　when　the　working　fluid　is　nitrogen　gas,　however,　the　decrement　can　be　neglected　for　distilled　water　as　the　working　fluid.