The construction of the lower cross-beam structure of the main tower of Changtai Changjiang River Bridge has the characteristics of high construction height，large amount of concrete earth volume，and difficult control of down-warping deformation.In order to implement the pouring of the lower cross-beam of the main tower，floor-type steel pipe supports were set at the lower cross-beam，which were used to support the lower cross-beam formwork and bear the load during the concrete pouring.Through the finite element software analysis and calculation，it was found that the asymmetric deformation of the main structure of the lower cross-beam could be effectively controlled，and the overall force of the supports could be optimized by setting the splayed steel pipe supports in the midspan of the longitudinal beam of the lower cross-beam and making broken joints in the midspan and side span of the longitudinal beam.The supports were assembled，welded，and accepted on the ground.Then they were lifted and fixed to the installation level after completion.The combination of theoretical calculation and construction process reduces the high-altitude operation，effectively guarantees the construction quality and efficiency of the supports，improves the pouring quality of the lower cross-beam of the main tower，and achieves remarkable economic benefits.