The invention discloses a cable-stayed bridge warren steel truss cantilever erection method, and relates to the bridge construction technical field; when main tower bottom end rail construction is finished, a pillar holder is set up; steel truss units are arranged on the pillar holder in a scattered manner and positioned on pillar top internode; an upper bridge floor on two ends of the pillar top internode is respectively provided with a girder crane, and the two girder cranes simultaneously work on two sides of the main tower; in normal construction, the girder crane on each side of the main tower firstly splices a lower bridge floor, having pre-spliced diagonal web members, with a lower bridge floor having the steel truss units arranged in the previous time; the girder crane then splices an upper bridge floor with an upper bridge floor having the steel truss units arranged in the previous time; finally, the girder crane walks an internode distance to the to-be-mounted side, hangs and tensions stab cables; the said normal construction mode is repeated for splicing until reaching a position above an auxiliary pillar or a closure internode. The cable-stayed bridge warren steel truss cantilever erection method can reduce production cost without affecting construction speed.