In　this　paper,　a　latent　heat　thermal　storage　device　is　designed　and　manufactured.　The　device　uses　flat　micro　heat　pipe　arrays　as　the　core　heat　transfer　element,　multichannel　flat　pipes　as　the　heat　transfer　fluid　channel　to　provide　and　remove　heat,　and　offset　strip　fins　to　strengthen　the　heat　exchange　of　the　phase　change　material　side.　The　performance　of　the　device　under　different　operating　conditions　was　explored,　and　a　3D　computational　fluid　dynamic　model　of　the　device　is　established.　The　model　is　simplified　by　using　the　method　of　equivalent　thermal　conductivity　and　equivalent　specific　heat　capacity.　The　performance　of　a　latent　heat　storage　unit　under　small　temperature　difference　is　also　studied.　Results　show　that　the　inlet　temperature　of　fluid　has　a　great　influence　on　the　performance　of　the　device.　During　charging　process,　when　the　fluid　temperature　changes　from　63　degrees　C　to　73　degrees　C,　the　charging　power　increases　from　921.1　W　to　1302.1　W　(41.3%).　During　discharging　process,　when　the　fluid　temperature　decreases　from　18　degrees　C　to　8　degrees　C,　the　discharging　power　increases　from　831.1　W　to　1210.5　W　(48.9%).　Regarding　the　flow　rate,　when　the　fluid　flow　rate　increases　from　2　L/min　to　3　L/min　(50%),　the　average　charging　power　increases　from　1,069.2　W　to　1,199.3　W　(12.2%),　and　the　average　discharging　power　increases　from　895.1　W　to　1,068.3　W　(19.3%).　Simulation　results　show　that　the　phase　change　material　in　the　thermal　storage　unit　can　melt　completely　when　the　temperature　difference　is　4　degrees　C,　but　the　melting　time　is　longer　when　the　heat　transfer　temperature　difference　is　less　than　6　degrees　C.　Heat　transfer　temperature　difference　refers　to　the　variance　between　the　heat　transfer　fluid　inlet　temperature　and　the　phase　change　material　phase　transition　temperature.　The　main　thermal　resistance　is　concentrated　in　the　part　where　multichannel　flat　pipes　transfer　heat　to　the　flat　micro　heat　pipe　arrays　and　the　phase　change　material　side.