The invention discloses a method for constructing a block prefabricated pre-tensioning prestressed corrugated steel web combined box girder. The combined box girder comprises a combined girder body formed by longitudinally connecting multiple H-shaped girder body units, and each H-shaped girder body unit is formed by splicing prefabricated concrete top plates, a prestress concrete bottom plate and a corrugated steel web which are all independently prefabricated. Each H-shaped girder body unit comprises one prestress concrete bottom plate and at least two prefabricated concrete top plates. An upper shearing force connecting piece, a top plate transverse connection steel rib, a top plate longitudinal connection steel rib and a top plate prestress channel are preburied in each prefabricated concrete top plate. Each prestress concrete bottom plate is of a flat plate structure, and a pre-tensioning prestressed steel cable, a lower shearing force connecting piece and a bottom plate longitudinal connection steel rib are preburied in each prestress concrete bottom plate. Bolt holes are reserved in the peripheries of the corrugated steel webs. The girder body is erected in a block prefabricated splicing structure mode, the sizes and the weights of the parts are correspondingly small, transport is stable, hoisting is safe, and construction is benefited.