The　wall　temperature　and　the　axial　wall　heat　conduction　for　steel　microtube　under　forced　convection　are　experimentally　studied,　when　distilled　water　and　nitrogen　gas,　as　the　working　fluids,　flow　through　a　stainless　steel　microtube　with　inner　diameter　168　μm　and　outer　diameter　406　μm.　By　using　direct　electrical　heating　method,　the　wall　temperature　field　photos　of　microtube　under　constant　Reynolds　number＇s　flow　and　different　heating　powers　are　acquired　by　employing　an　infrared　themoviewer　and　specially　magnifying　lens.　Manipulating　and　amending　the　field　photos,　the　exact　temperature　distribution　along　the　wall　of　the　microtube　is　gained　and　the　quantity　of　the　axial　conductive　heat　is　also　obtained.　The　experimental　results　show　that　the　ratio　of　the　quantity　of　the　axial　conductive　heat　to　that　of　whole　heating　is　about　2.1%.