Abstract: In order to solve the problems of construction accuracy, and the hoisting of the long-span steel structure assembly pedestrian bridge, the geometric modeling and meshing of the steel structure flyover are carried out through BIM+Midas Gen finite element analysis software, and a three-dimensional space model is established, and a series of measures including structural analysis, segmentation and section optimization, and installation method optimization are implemented, and the application of steel structure two-dimensional code traceability management system is enhanced to establish a model of steel structure and hoisting components, which can quickly and accurately complete the structural analysis and design, and make the hoisting force analysis rapid, accurate, visualized. The results show that the geometric structure characteristics of the steel structure flyover can be obtained by using BIM+Midas Gen finite element analysis software to establish a three-dimensional space model, and then the cutting data of the intersecting line is generated by controlling the three-dimensional coordinate points and programmed by the intersecting line programming software, and the cutting data is input into the cutting machine for pipe fitting cutting, so as to maximize the accuracy of the intersecting line cutting of steel pipes. The research results can also provide new ideas for the hoisting, assembly and welding construction of the steel structure of the pedestrian bridge with a span diameter of more than 30 m.