The　blade　tip　region　of　the　shroud-less　high-pressure　gas　turbine　is　exposed　to　an　extremely　operating　condition　with　combined　high　temperature　and　high　heat　transfer　coefficient.　It　is　critical　to　design　new　tip　structures　and　apply　effective　cooling　method　to　protect　the　blade　tip.　Multi-cavity　squealer　tip　has　the　potential　to　reduce　the　huge　thermal　loads　and　improve　the　aerodynamic　performance　of　the　blade　tip　region.　In　this　paper,　numerical　simulations　were　performed　to　predict　the　aerothermal　performance　of　the　multi-cavity　squealer　tip　in　a　heavy-duty　gas　turbine　cascade.　Different　turbulence　models　were　validated　by　comparing　to　the　experimental　data.　It　was　found　that　results　predicted　by　the　shear-stress　transport　with　the　γ-Reè　transition　model　have　the　best　precision.　Then,　the　film　cooling　performance,　the　flow　field　in　the　tip　gap　and　the　leakage　losses　were　presented　with　several　different　multi-cavity　squealer　tip　structures,　under　various　coolant　to　mainstream　mass　flow　ratios　(MFR)　from　0.05%　to　0.15%.　The　results　show　that　the　ribs　in　the　multi-cavity　squealer　tip　could　change　the　flow　structure　in　the　tip　gap　for　that　they　would　block　the　coolant　and　the　leakage　flow.　In　this　study,　the　case　with　one-cavity　(1C)　achieves　the　best　film　cooling　performance　under　a　lower　MFR.　However,　the　cases　with　multi-cavity　(2C,　3C,　4C)　show　higher　film　cooling　effectiveness　under　a　higher　MFR　of　0.15%,　which　are　32.6%,　34.2%　and　41.0%　higher　than　that　of　the　1C　case.　For　the　aerodynamic　performance,　the　case　with　single-cavity　has　the　largest　total　pressure　loss　coefficient　in　all　MFR　studied,　whereas　the　case　with　two-cavity　obtains　the　smallest　total　pressure　loss　coefficient,　which　is　7.6%　lower　than　that　of　the　1C　case.　©　2021　American　Society　of　Mechanical　Engineers　(ASME).　All　rights　reserved.