The invention discloses a bridge girder erection machine set and a technology for automatically enabling the bridge girder erection machine to transfer among bridges. According to the bridge girder erection machine set, a dual-straddle type double-girder three-support scheme is adopted, and two tyre-type power-driven small-size trolleys are used as girder transporting vehicles and can be used for carrying T-shaped concrete girders with the span of 32m. When a bridge girder erection machine longitudinally moves through a hole, the two trolleys are respectively arranged at the bottoms of an intermediate support leg and a rear support leg to form a traveling trolley of the bridge girder erection machine, and at the moment, the bridge girder erection machine set passes through the hole at a front cantilever state; and when the bridge girder erection machine needs to transfer among bridges, the two trolleys are used as carrying trolleys, namely the two trolleys are respectively used as the girder transporting trolleys, the traveling trolleys and the carrying trolleys in turn. A series of operation methods, such as transferring among bridges, passing through tunnels and mounting in position of the bridge girder erection machine per se on a bridge opening when a first-hole girder of a next bridge is erected, can be finished in a self-help way through the matching of the multifunctional trolleys to the bridge girder erection machine; and compared with the prior art, the bridge girder erection machine is more advanced and economic.