Abstract:The theoretical calculation methods of unstressed configuration of the main girder and the installation alignment of the whole bridge in the alignment control of the long-span cantilever assembled steel box girder cable-stayed bridge are put forward. Taking a double-pylon steel box girder cable-stayed bridge in Nanning as the engineering background, the unstressed configuration of each girder and the installation alignment of the whole bridge are obtained by establishing the local model of the girder under the hoisting condition and the overall model simulating the construction process. A modified formula for the installation elevation of the steel box girder considering the temperature effect is proposed, which provides a reference for the alignment control of the similar projects in the future.