In the long-span cable-stayed bridge, the pylon is an important part of the structure, and the construction quality of the pylon directly affects the service life and safety performance of the whole bridge. It is necessary to conduct analysis on the stress and deformation of the pylon during construction. The Guanyinsi Changjiang River Bridge is a hybrid girder cable-stayed bridge with a main span of 1160 m. The pylons are A-shaped structure rising 262 m, which belongs to ultra-high hybrid pylons with special-shaped composite section. In order to ensure that the deformation and stress of the ultra-high pylon meet the design requirements and realize the safety of construction, this paper established the finite element model of the whole construction process of the pylon based on the spatial grid model, a practical and precise calculation method, to study how deformation and stress change during construction and propose relevant control measures. The results indicate that the installation of temporary horizontal bracing bars and the application of jacking forces can effectively reduce the displacement of the pylon columns and the tensile stress of concrete during construction, so as to avoid the cracking of concrete. The horizontal deformation of the pylon can be controlled within 5 mm by applying 6 temporary bracing bars and corresponding jacking forces. In addition, the removal sequence of temporary bracing bars has little effect on the deformation and stress redistribution of the pylon, which can be ignored.