The　superior　capillary　wicking　capability　of　hierarchical　surfaces　determined　by　the　capillary　pressure　and　viscous　resistance　plays　a　critical　role　in　developing　the　high-efficient　thermal　management　devices.　In　this　study,　a　novel　chemical　oxide　method　for　fabricating　the　in　situ　micro/nanocrystal　structures　on　the　copper　substrates　with　prominently　improved　capillary　wicking　capability　is　proposed.　Single-scaled　and　hierarchical　structures　can　be　fabricated,　and　the　capillary　wicking　capability　of　the　hierarchical　structures　exhibits　the　much　higher　wicking　coefficient　than　that　of　the　single-scaled　structures.　The　wicking　coefficient　on　the　nanosheet　and　micro-flowers　hierarchical　surface　was　measured　as　3.77 mm/s0.5,　which　indicates　a　maximum　improvement　of　146.4%　compared　to　single-scaled　structures.　This　hierarchical　structure　can　provide　two-tier　pores　for　strengthening　the　capillary　pressure　driven　by　the　nanoscale　pores　and　reducing　the　viscous　resistance　driven　by　the　micropores.　It　is　worth　noting　that　the　ultrafast　wicking　on　the　hierarchical　surface　is　useful　in　creating　extremely　effective　thermal　management　systems　and　advanced　heat　exchangers.　©　2023,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.