An　experiment　was　conducted　on　a　prestressed　concrete　(PC)　composite　girder　bridge　with　steel　truss　webs　to　investigate　its　flexural　performance.　The　mechanical　characteristics　and　failure　modes　of　a　PC　composite　girder　bridge　with　steel　truss　webs　was　clarified.　Finite　element　(FE)　analysis　was　carried　out,　and　the　influence　of　the　girder　height-to-span　ratio　and　eccentric　loading　effect　on　the　flexural　performance　of　a　composite　beam　bridge　with　a　steel　truss　web　was　discussed.　The　method　for　calculating　the　cracking　bending　moment,　the　bending　moment　at　the　rebar　yield　stage,　and　the　ultimate　bending　moment　of　a　PC　composite　girder　with　steel　truss　webs　was　proposed.　Key　findings　include　that,　in　both　the　elastic　and　cracking　elastic　stages,　the　strain　of　the　bottom　and　top　conforms　to　the　plane-section　assumption.　Throughout　the　loading　process,　there　was　no　occurrence　of　joint　failure　or　local　buckling　failure　in　the　steel　truss　webs;　the　composite　girder　ultimately　fails　due　to　excessive　deformation,　indicating　that　the　overall　mechanical　performance　of　the　composite　beam　is　good.　The　deflection　and　stress　in　the　mid-span　section　decrease　with　an　increasing　height-to-span　ratio,　and　there　are　significant　impacts　of　eccentric　loading　on　deflection　and　stress.　Compared　with　the　results　of　the　FE　analysis　and　test,　the　calculation　methods　of　the　cracking　moment,　reinforcement　yield　moment,　and　ultimate　moment　of　PC　composite　girders　with　steel　truss　webs　presented　in　this　paper　have　a　high　accuracy.