In　order　to　research　the　toughness　characteristics　of　hybrid　fiber　on　ultra-high　performance　concrete(UHPC),　161　specimens　of　three-point　bending　beam　fracture　testing　of　UHPC　reinforced　with　four　type　fibers　and　various　contents　have　been　conducted.　The　load-crack　mouth　open　displacement　(CMOD)　curves　and　load-deflection　curves　were　measured.　We　took　the　peak-load　CMOD　of　plain　UHPC　as　the　reference　initial　CMOD　value　of　hybrid　fibers　reinforced　UHPC.　Based　on　the　load-CMOD　curves,　a　characterization　method　of　equivalent　fracture　toughness　was　proposed.　This　new　method　has　clear　physical　meaning,　and　unveils　the　influence　rule　of　hybrid　fibers　type　and　contents　to　fracture　toughness　of　UHPC.　The　research　shows　that　the　toughness　of　UHPC　depends　on　the　content　of　steel　fiber　in　small　deformation　stage　(less　than　the　50　times　CMOD　value　of　plain　UHPC　at　peak　load)　and　macro-synthetic　fiber　plays　toughening　effect　in　middle　deformation　and　large　deformation　stage　(larger　than　the　50　times　CMOD　value　of　plain　UHPC　at　peak　load).　©　2016,　BUAA　Culture　Media　Group　Ltd.　All　right　reserved.