In　order　to　improve　the　flow　and　heat　transfer　performance　of　the　negative　pressure　low　temperature　plate-fin　heat　exchanger　in　superfluid　helium　system,　a　new-type　sine-offset　fin　was　proposed　by　combining　traditional　offset　fin　and　sine-wavy　fin,　and　the　offset　density　was　proposed　as　a　new　structural　parameter　to　describe　the　new　sine-offset　fin.　The　physical　field　of　flow　and　heat　transfer　in　sine-offset　fin　channel,　the　comparison　of　flow　and　heat　transfer　performance　in　three　kinds　of　fin　channels,　and　the　influence　of　fin　structural　parameters　on　fin　performance　were　studied　and　analyzed　by　numerical　simulation.　The　results　show　that　compared　with　traditional　offset　fin　and　sine-wavy　fin,　the　heat-transfer　factor　j　of　the　sine-offset　fin　was　increased　by　19.97%-38.22%　and　25.09%-33.83%,　respectively,　and　the　improvement　of　the　comprehensive　performance　is　more　obvious　at　lower　Reynolds　numbers;　the　j　factor　decreases　with　the　increase　of　wavelength　and　offset　density,　and　increases　with　the　double　waveheight.　In　addition,　the　friction　factor　f　decreases　with　the　wavelength　and　increases　with　the　double　waveheight,　and　increases　first　and　then　decreases　with　the　increase　of　offset　density.　The　new　sine-offset　fin　structure　can　improve　the　heat　transfer　and　comprehensive　performance　of　plate-fin　heat　exchanger.　This　research　may　provide　a　reference　for　the　optimal　design　of　plate-fin　heat　exchanger.　©　2021,　Editorial　Office　of　Journal　of　Xi＇an　Jiaotong　University.　All　right　reserved.