In　order　to　investigate　the　flow　characteristics　and　film　cooling　performance　of　novel　merged　holes　cooling　method,　merged　cylindrical　holes　structures　have　been　applied　on　a　flat　plate　with　three　merging　ratios　under　three　blowing　ratios.　Single　cylindrical　hole　film　cooling　structure　is　also　established　as　a　benchmark　structure.　The　numerical　results　of　the　single　cylindrical　hole　are　validated　with　the　experimental　results　available　in　open　literatures.　The　discharge　coefficient,　aerodynamic　loss,　tangential　velocity　vectors　and　total　vorticity　distributions　are　studied　and　compared.　The　spanwise　averaged　film　cooling　effectiveness　and　adiabatic　temperature　contours　are　studied　and　compared.　Results　show　that　the　development　of　the　kidney　vortex　is　impeded　and　the　film　cooling　performance　is　promoted　in　merged　holes　cooling　cases.　The　blowing　ratio　and　merging　ratio　both　affect　the　cooling　performance　of　merged　holes　cooling　cases.　In　this　paper,　the　best　film　cooling　performance　is　obtained　at　the　biggest　merging　ratio.　©　2019,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.