Abstract: Aiming at the industry problems such as uncontrolled welding deformation and insufficient segment matching accuracy of the steel shell of steel-concrete composite towers in long-span bridges, which are caused by thin-wall characteristics, complex curved shapes and dense stiffeners, an integrated technical scheme of "phased precise control + multi-process collaborative optimization" is innovatively proposed. The scheme covers four core links: refined manufacturing of wall plate units, efficient assembly of segment blocks, three-dimensional assembly of integral segments and precise forming at the bridge site. Through key technologies such as differentiated processing of bolt holes, structure-adaptive welding processes, intelligent assembly positioning systems and active control of welding stress, a full-process quality assurance system is constructed. Verified by the practice of major projects such as the Anlu Yellow River Bridge and the Shiziyang Bridge, after applying this technology, the flatness error of the steel shell wall plate unit is ≤2mm, verticality of segmental assembly ≤1.5mm/m, and the one-time qualification rate of welds reaches more than 99.7%, which significantly improves the manufacturing efficiency and structural reliability of composite towers, and provides a replicable technical paradigm for similar projects.