A　total　of　33　four-point　bending　beam　tests　were　conducted　to　investigate　the　contribution　of　the　single　addition　of　steel　fiber　(SF),　SF　blended　with　coarse　polyolefin　fiber,　polyvinyl　alcohol　fiber,　polyester　fiber,　glass　fiber,　and　basalt　fiber　to　study　the　toughening　characteristics　of　hybrid　fiber-reinforced　ultra-high　performance　concrete　(UHPC)　and　to　improve　the　bending　toughness　of　UHPC　beams.　The　influence　of　fiber　type　and　geometric　size　on　the　toughening　effect　of　the　beam　was　analyzed,　and　the　cross-sectional　shape　of　the　specimen　was　scanned　by　an　electron　microscope.　Results　showed　that　compared　with　the　single-doped　SF,　the　hybrid　fiber　UHPC　had　better　bending-deflection　hardening　properties　and　retained　higher　bearing　capacity　in　the　late　stage　of　deformation.　The　hardening　index　proposed　in　this　study　can　well　characterize　the　hardening　properties　of　the　hybrid　fiber　UHPC.　In　this　study,　the　toughening　characteristics　and　mechanism　of　the　hybrid　fiber　UHPC　were　clarified,　and　the　evaluation　index　of　the　flexural　toughness　of　the　hybrid　fiber　UHPC　was　proposed.　This　index　can　provide　a　reference　for　practical　engineering　applications.　©　2023　Editorial　Board　of　Journal　of　Harbin　Engineering.　All　rights　reserved.