To　slove　the　heat　transfer　problem　of　electronic　chips,　this　paper　studied　the　fluid　flow　and　heat　transfer　condition　when　deionized　water　flew　through　the　microchannel　heat　sink.　The　heat　sink　was　welded　by　cooper　and　the　microchannel　had　a　hydraulic　diameter　of　0.23　mm.　The　heating　flux　was　2×106　W/m2　and　the　Re　was　between　252　and　1　060.　Results　show　that　the　periodically　changeable　cross-sections　microchannel　heat　sink　with　triangular　reentrant　cavities　has　a　better　performance　than　conventional　rectangular　microchannel　heat　sink,　and　both　the　heating　surface＇s　average　temperature　and　maximum　temperature　of　the　former　is　2-3℃　lower　than　the　later　one　and　the　pressure　loss　difference　between　the　two　heat　sinks　is　small;　with　the　increase　of　the　flow　rate　the　heating　surface＇s　average　temperature　is　reduced;　when　the　flow　rate　increases　to　a　appropriate　degree,　the　temperature　change　will　not　be　obvious,　and　it　suggests　that　the　heat　transfer　performance　cannot　be　enhanced　only　by　increasing　the　power　of　pumps.　©,　2015,　Beijing　University　of　Technology.　All　right　reserved.