The invention relates to the technical field of assembly, in particular to a positioning and lifting system for a large structural member. The positioning and lifting system for the large structural member comprises lifting devices and a limiting device, wherein the lifting devices comprise lifting plate assemblies, spiral elevators, guide mechanisms, falling prevention mechanisms and bases, the spiral elevators and the guide mechanisms are both arranged on the bases, the lifting plate assemblies are driven to lift through the spiral elevators, the guide mechanisms are provided with guide columns, the lower sides of the lifting plate assemblies and the upper ends of the guide columns are fixedly connected, the lower ends of the guide columns extend into the bases, the falling prevention mechanisms are arranged in the bases, the falling prevention mechanisms correspond to the guide mechanisms one by one, the falling prevention mechanisms comprise limiting sliding blocks and air cylinders, the lower parts of the guide columns are provided with notches, when the lifting plate assemblies are lifted in place, the limiting sliding blocks are driven by the air cylinders to move and be clamped in the notches on the corresponding guide columns, and lifting detection assemblies are arranged on the base. An in-place detection assembly is provided on either lifting device. The positioningand lifting system for the large structural member ensures the safety and improves the automation level and the working efficiency of a production line.