Fiber　reinforcement　polymer　(FRP)　has　high　strength　and　high　stiffness-to-weight　ratio,　which　owns　potential　to　be　used　as　prestressing　tendons　in　corrosive　environment.　However,　concrete　beams　have　showed　brittle　flexural　failure　due　to　the　elastic　rupture　of　FRP　tendons.　In　order　to　improve　the　ductility,　a　combination　of　bonded　and/or　unbonded　prestressing　tendons　is　used.　The　flexural　capacity　of　concrete　beam　prestressed　with　bonded　and/or　unbonded　FRP　tendons　has　been　studied　theoretically.　According　to　the　definition　of　balanced　ratio,　the　failure　modes　of　concrete　beams　prestressed　with　FRP　tendons　were　defined　in　this　paper,　and　the　balanced　ratio　and　the　corresponding　formula　for　calculating　the　flexural　strength　were　derived.　In　order　to　verify　the　correctness　of　the　formula,　a　series　of　flexural　tests　were　conducted　on　9　concrete　beams　prestressed　with　bonded　and/or　unbonded　FRP　tendons.　The　test　program　validated　the　proposed　method.　The　results　of　experiments　show　that,　if　the　reinforcement　of　prestressed　beam　remains　the　same,　the　concrete　beam　prestressed　with　bonded　FRP　tendons　has　the　highest　carrying　capacity,　followed　by　the　unbonded　prestressed　beam,　while　the　external　unbonded　prestressed　beam　without　deviators　has　the　lowest　carrying　capacity.　Through　combination　of　different　FRP　tendons,　the　ductility　of　concrete　beams　prestressed　with　FRP　tendons　can　be　improved.