In　this　paper,　Reynolds-averaged　Navier–Stokes　equations　with　the　standard　k−Ε　turbulent　model　and　Multiple　Reference　Frame　model　were　used　to　simulate　the　performance　of　axial　flow　fan.　The　simulation　results　were　compared　with　the　existing　experimental　data,　and　the　reliability　of　the　existing　numerical　simulation　method　was　verified.　Then,　the　variable　velocity　circulation　design　method　was　used　to　redesign　the　fan　blades.　Four　types　of　blades　were　established　using　different　circulation　indexes　(m　=　0.2,　0.5,　0.7,　and　1.0).　The　performance　of　the　four　redesigned　fans　was　calculated　by　numerical　simulation.　The　influence　of　circulation　index　on　configuration　parameters　was　studied.　Results　show　that　the　efficiencies　of　the　redesigned　fans　were　higher　than　the　original　one.　The　efficiency　of　optimal　designed　fan　could　reach　70%,　which　is　35%　higher　than　the　original　fan.　Besides,　the　influence　of　the　selected　value　of　design　efficiency,　lift　coefficient,　and　c/R　during　the　design　process　on　the　fan　efficiency　was　also　discussed　in　the　paper.　©　2020,　Springer　Nature　Singapore　Pte　Ltd.