This　work　studied　the　capillary　flow　enhancement　with　Fe3O4-water　nanofluids　in　a　microgrooves　wick　when　the　groove　is　hotter　than　the　fluid.　Capillary-rise　experiment　was　conducted　to　derive　three　parameters,　Delta　P-cap　center　dot　K,　capillary　pressure　and　Poiseuille　number　for　evaluating　the　flow　on　flow　driving　force　and　resistance.　Results　show　that　the　hotter　groove　promotes　the　enhancement　by　making　it　easier　for　the　nanofluids　to　induce　friction　reduction.　When　the　temperature　difference　between　the　groove　and　liquid　pool,　Delta　T　is　about　15　degrees　C,　the　nanofluids　lead　to　a　76%　increase　in　Delta　P-cap　center　dot　K　and　42%　decrease　in　Poiseuille　number　on　average,　which　is　30　and　15　percentage　points　larger　than　that　for　Delta　T　of　zero　respectively.　Furthermore,　it　requires　optimizing　the　concentration　and　Delta　T　for　raising　the　enhancement　with　the　nanofluids.　However,　the　capillary　pressure　is　slightly　affected　by　the　nanofluids　when　the　groove　is　hotter.　At　the　optimal　concentration,　the　capillary　pressure　even　becomes　almost　independent　of　Delta　T.　The　mechanism　is　explained　with　how　the　hotter　groove　can　change　the　particle　migrations　that　exist　in　the　groove　cross-section　and　determine　the　wetting　and　friction　reduction　of　a　nanofluid.