The invention discloses a steel and concrete combined box girder concrete wing plate formwork and a construction method. The formwork comprises a plurality of supporting cross beams, a plurality of supporting longitudinal beams, two supporting stand columns, a plurality of pull rods, a plurality of nuts, a plurality of gaskets, a plurality of longitudinal ridges, a plurality of steel cover plate brackets and a plurality of steel cover plates. The steel and concrete combined box girder concrete wing plate formwork and the construction method have the beneficial effects that the steel cover plates are arranged on top plates of erected steel box girders for forming a formwork system with the steel box girders, so that the problems of road crossing construction and non-bracket construction are solved, in the specific construction, the installation can be completed only by manual operation without the matching of large-scale hoisting equipment, and the elevation of a die block can be very conveniently and precisely adjusted, so that the precision is high; and in addition, for wing plates of different sizes, only formwork equipment with different specifications is needed to be manufactured, the used formwork equipment materials are fewer and are all common structural steel for engineering, the processing difficulty is small, the use is simple, and the site construction use is facilitated, so that the construction period is shortened, and the construction cost is low.