Headed　studs　are　key　connectors　to　transfer　the　interfacial　shear　force　between　the　steel　and　concrete　component　in　steel　ultra-high　performance　concrete　(UHPC)　composite　structures.　This　paper　presented　a　systematic　study　on　the　shear　behavior　of　headed　studs　embedded　in　UHPC.　A　total　of　30　push-out　tests,　categorized　into　10　groups,　were　conducted　to　investigate　the　effects　of　length-to-diameter　ratio　of　stud,　fiber　content,　compressive　strength　of　concrete,　and　diameter　of　studs.　The　load-slip　curve,　shear　strength,　shear　stiffness,　and　ductility　of　studs　were　analyzed.　The　test　results　showed　that:　(i)　the　shear　strength　and　stiffness　of　studs　embedded　in　UHPC　were　higher　than　those　in　normal　concrete　(NC),　while　the　ductility　was　lower;　(ii)　the　shear　strength　increased　with　increasing　diameter　of　studs;　and　(iii)　the　length-to-diameter　ratio　of　studs　(3.75-10.0)　and　fiber　content　(0%-2%)　had　a　limited　effect　on　the　shear　strength　and　stiffness.　Results　from　the　tests　were　used　to　evaluate　the　existing　design　methods,　which　were　found　to　be　relatively　conservative　for　estimating　the　shear　strength　of　headed　studs　embedded　in　UHPC.　New　equations　were　then　proposed　to　estimate　the　load-slip　curve　and　shear　strength　of　headed　studs　embedded　in　UHPC.