Method adopting vertical stay ropes to construct steel-concrete composite girders

The invention discloses a method adopting vertical stay ropes to construct steel-concrete composite girders. Firstly, steel girder units are prefabricated, multiple temporary suspending pieces are arranged on flanges of steel girders in a spaced way, and meanwhile multiple groups of stay rope devices are correspondingly designed on a bridge girder erection machine; during construction, first holedsteel girder units are erected in place, then suspension clasps at the bottoms of the stay ropes on the bridge girder erection machine are connected with the suspending pieces on the flanges of steelgirders to make the stay ropes in a vertical state, then rope forces of the stay ropes reach set value through stretching and drawing, and then the stay ropes are locked; prefabricated concrete bridge deck slabs are installed; bridge deck slab wet joint concrete is poured, and after the bridge deck slab wet joint concrete reaches the design strength, connection between the stay ropes and the suspending pieces is relieved;