This　paper　presents　the　experimental　results　of　laminar　flow　behavior　of　water　in　circular　micro　pin-fin　(C-MPF),　square　micro　pin-fin　(S-MPF)　and　diamond　micro　pin-fin　(D-MPF)　heat　sinks　using　micro-PIV　flow　visualization　technology　at　first.　All　three　micro　pin-fin　heat　sinks　have　a　hydraulic　diameter　of　200　mu　m.　Second,　numerical　simulation　results　of　the　fluid　flow　characteristics　in　these　heat　sinks　with　CFD　are　compared　to　the　experimental　results　of　fluid　flow　behaviors　measured　with　the　micro-PIV　flow　visualization.　The　normalized　time　averaged　streamline　patterns　and　instantaneous　velocity　contours　in　the　three　heat　sinks　were　obtained　for　laminar　flow　of　Reynolds　number　from　10　to　200.　By　comparison,　the　experimental　results　favorably　agree　with　the　simulated　results　of　fluid　flow.　Of　the　three　types　of　heat　sinks,　the　vortexes　occur　the　earliest　in　the　D-MPF　heat　sink,　which　also　present　very　complicated　back　flow.　The　strong　vortexes　and　back　flow　effectively　enhance　the　mixing　of　fluid　and　therefore　lead　to　higher　pressure　drops　in　the　D-MPF　heat　sink　as　compared　to　the　other　two　types　of　heat　sinks.　The　vortexes　in　the　D-MPF　heat　sink　are　very　much　easily　involved　in　the　main　flow　than　those　in　the　other　two　types　of　heat　sinks　due　to　the　high　deceleration　and　pressurization　zone.　Finally,　numerical　simulation　results　of　heat　transfer　at　steady　state　in　the　three　heat　sinks　are　presented.　The　initial　temperature　of　the　working　fluid　and　the　ambient　air　is　maintained　at　293　K　and　a　constant　heat　flux　of　q(w)　=　400　kW/m(2)　is　adopted　in　the　central　area　at　the　bottom　of　the　heat　sink.　The　Reynolds　number　ranges　from　40　to　300　for　the　fluid　flow　and　heat　transfer　simulations.　It　shows　that　D-MPF　heat　sink　has　better　heat　transfer　performance　than　the　other　two　type　heat　sinks.　The　combined　effects　of　the　vortex　in　the　main　flow　at　the　front　side　wall　and　the　strong　vortex　intensity　behind　the　D-MPF　heat　sink　obtained　in　both　experimental　and　numerical　results　may　reasonably　explain　the　better　heat　transfer　enhancement　behaviors　as　compared　to　those　in　the　other　two　types　of　heat　sinks.　Further　experiments　on　the　heat　transfer　performance　will　be　conducted　to　compare　to　the　simulated　results　in　the　follow-up　planned　research.　(C)　2017　Elsevier　Masson　SAS.　All　rights　reserved.