To　improve　the　performance　of　the　micro-channel　condenser　outside　the　tank　of　domestic　air　source　heat　pump　water　heater,　a　quasi-steady　state　model　of　the　household　air　source　heat　pump　water　heater　with　microchannel　condenser　was　established.　The　experimental　results　show　that　the　model　error　can　be　controlled　within　±　9%.　The　heat　transfer,　heat　transfer　coefficient,　and　pressure　drop　of　the　microchannel　condenser　were　simulated　by　the　model.　Results　show　that　when　the　microchannel　condenser　has　four　processes,　the　pressure　drop　can　be　reduced　while　the　heat　transfer　is　guaranteed.　The　optimal　size　of　microchannel　cross　section,　a　key　parameter,　is　between　1.6　and　2.6　mm2.　The　system　performance　is　optimal,　and　the　number　of　microchannels　in　the　flat　tube　should　be　controlled　within　16-24.　The　research　results　provide　reference　for　the　design　of　micro-channel　condenser　of　household　air　source　heat　pump　water　heater.　©　2024　Beijing　University　of　Technology.　All　rights　reserved.