The utility model relates to a span wire platform for construction of large -span steel beam mounting, it sets up in the girder steel below, and it includes steel -pipe column, cantilever, bearing wire rope, the wire rope that sweeps the floor, ledger board and Z type jib, wherein, the cantilever welding is between two steel -pipe columns, and the welding has two -layer otic placode from top to bottom on it, bearing wire rope connects between lower floor's otic placode, the wire rope that sweeps the floor connects between upper otic placode, its and the ligature of Z type jib, the ledger board is laid on bearing wire rope, install on the girder steel on the top of Z type jib, and the bottom is supported bearing wire rope. The utility model discloses a difficulty has simple structure, safe and reliable, time limit for a project weak point, with low costs, a great deal of advantages such as construction easy operation that is used for the suspension bridge platform of large -span steel beam mounting construction can't set up the scaffold in having overcome the river course .