To　investigate　the　load　transfer　mechanism　and　stress　performance　at　the　interface　of　prefabricated　Ultra　High　Performance　Concrete　(UHPC)　and　cast-in-place　Normal　Concrete　(NC),　flexural　tests　for　normal　bond　strength　and　direct　shear　tests　for　tangential　bond　strength　were　conducted.　The　influence　of　steel　fiber　content,　interface　roughness,　and　NC　strength　on　the　interfacial　tensile　and　shear　performance　was　analyzed.　A　calculation　method　for　the　interfacial　tensile　and　shear　strength　of　prefabricated　UHPC　and　cast-in-place　NC　was　established.　The　results　show　that　the　failure　mode　of　specimens　with　lower　interface　roughness　is　interface　failure,　while　specimens　with　higher　interface　roughness　exhibit　cohesive　failure　within　the　NC　matrix　during　UHPC-NC　interface　failure.　Steel　fiber　content,　interface　roughness,　and　concrete　compressive　strength　significantly　affect　the　interfacial　tensile　and　shear　strength　of　prefabricated　UHPC　and　cast-in-place　NC.　The　proposed　calculation　method,　which　considers　the　influence　of　interface　roughness,　steel　fiber　content,　and　NC　strength,　showed　that　the　calculated　values　were　in　good　agreement　with　the　experimental　values,　with　errors　within　an　acceptable　range,　thereby　verifying　the　validity　and　accuracy　of　the　proposed　formula.　©　2025　Elsevier　Ltd