In　recent　years,　surfaces　with　nanocavities　have　been　identified　to　considerably　improve　boiling　heat　transfer,　that　is　highly　promising　for　advanced　thermal　energy　systems.　To　boost　developments　in　nanostructured　boiling　surfaces,　effects　of　nanocavity　geometry　on　nucleate　boiling　at　the　nanoscale　are　systematically　studied　for　the　first　time　by　utilizing　molecular　dynamics　simulation.　Three　typical　nanocavities　with　rectangular,　semicircular,　and　triangular　cross-sectional　shapes　are　constructed,　which　have　the　identical　width　and　depth　(8　nm　and　4　nm).　Moreover,　three　representative　wetting　conditions　corresponding　to　different　solid-liquid　interaction　strengths　are　further　considered　to　provide　a　comprehensive　understanding　of　geometry　effects.　The　results　manifest　that　nanocavity　geometry　effect　on　nucleate　boiling　can　be　attributed　to　the　differences　in　their　solid-liquid　contact　area　and　solid-liquid　interactions　play　a　vital　role　in　reinforcement　effectiveness.　When　the　solid-liquid　interaction　is　sufficiently　strong　(energy　coefficient　equals　1.5,　termed　ultra-superhydrophilicity),　variations　in　nanocavity　geometries　will　induce　remarkable　effects　on　boiling　performance.　Among　three　geometric　configurations,　the　rectangular　nanocavity　exhibits　the　highest　heat　transfer　efficiency　and　achieves　maximum　boiling　enhancement,　including　significant　improvements　in　bubble　nucleation　and　growth,　as　well　as　critical　heat　flux.　This　study　provides　an　essential　insight　into　nanoscale　boiling　reinforcement　mechanism.