The utility model relates to a prefabricated prefabricated channel -section steel widening processing structure of simple beam of erectting between tunnel. Bridge between the tunnel all adopts the cast in situs scheme if precast box girder beam width can't satisfy fortune roof beam car or fortune frame all -in -one to be crossed the tunnel transportation and erect the requirement usually, because the traffic is not smooth usually between the tunnel, the distance is far away, and material and construction equipment be difficult taking one's place all, and just all fronts construction cycle is controlled to on -the -spot concreting construction cycle length. The utility model discloses set up prefabricated channel -section steel component in the precast box girder edge of a wing terminal surface outside, prefabricated channel -section steel component is the channel -section steel structure, and the notch is outside, the tank bottom in through precast box girder edge of a wing terminal surface pre -buried buried bolt in advance be fixed in precast box girder. The utility model discloses can be prefabricated in liang chang, liangchang is assembled in advance and is cup jointed, and the split adopts fortune roof beam car or the transportation of fortune frame all -in -one to take one's place to set up and cup joint, can simplify the site operation process by a wide margin and effectively shorten construction cycle to bridge between the tunnel, has obvious economic benefits.