CFST　composite　truss　girder　is　a　new　type　of　structure　that　consists　of　concrete　deck　slab,　upper　and　bottom　CFST　chords　and　steel　web　members.　Based　on　the　flexural　test　of　a　two-span　CFST　composite　truss　girder,　the　finite　element　model　was　established　and　the　mechanical　performance　of　the　structure　was　analyzed　in　this　paper.　At　the　same　time,　the　main　structural　parameters　including　the　angle　of　web　member　and　the　ratio　of　depth　to　span　were　introduced.　The　results　of　this　research　were　helpful　to　the　application　of　CFST　composite　truss　girder.