In　this　paper,　the　flow　and　heat　transfer　characteristics　of　the　unsteady　laminar　flow　developed　by　sinusoidal　change　of　the　inlet　velocity　in　the　two　structural　microchannels　were　studied　by　a　numerical　method.　The　effects　of　pulsation　frequency,　amplitude,　and　Re　on　the　flow　and　heat　transfer　in　the　microchannel　were　studied　respectively.　The　research　results　show　that　the　pulsating　flow　has　little　effect　on　the　bottom　surface　temperature　of　the　rectangular　channel　and　heat　transfer　in　the　Re　range　of　100　-　400,　but　it　has　a　significant　effect　on　the　microchannel　with　the　triangular　reentrant　cavities.　As　the　pulsation　frequency　increases,　the　bottom　surface　temperature　of　the　channel　increases　first　and　decreases　later.　It　is　proved　that　there　is　a　critical　frequency　that　causes　the　channel　bottom　temperature　to　increase　when　it　is　less　than　that　frequency　and　decreases　when　it　is　greater　than　that　frequency.　As　the　amplitude　increases,　the　wall　temperature　decreases　and　the　heat　transfer　continues　to　increase.　However,　as　the　Re　increases,　the　effect　of　pulsating　flow　gradually　decreases.　The　increase　of　pulsation　frequency　and　amplitude　increases　the　pressure　drop　of　the　microchannel.　©　2023　Beijing　University　of　Technology.　All　rights　reserved.