In　order　to　study　the　load　bearing　and　deformation　capacity　of　a　large-span　half　steel-plate-reinforced　concrete　(HSC)　beam,　a　static　test　of　a　scaled　down　(1:3)　simply　supported　specimen　is　conducted.　The　mechanical　characteristics　and　damage　process　of　the　HSC　specimen　are　investigated　by　analyzing　the　development　of　the　deflection,　strain　and　fracture　during　loading　process.　Good　combination　action　is　observed　during　the　test　in　steel　plates,　reinforcing　bars　and　concrete　in　HSC　beam;　and　the　specimen　has　good　mechanical　properties　of　high　bearing　capacity,　large　stiffness　and　high　ductility.　At　last,　the　calculation　formulae　for　the　bending　capacity　and　short-term　stiffness　of　the　composite　beam　in　existing　codes　are　examined　via　the　experimental　results　and　theoretical　analysis,　which　provides　a　reference　for　engineering　design.