Based on the structure of Chongqing Raffles High-altitude Corridor, this paper expounds the new methods and specific technical routes for large-scale complex steel structure deformation monitoring. Aiming at the problem that the point cloud data is difficult to be spliced in deformation monitoring, coordinate system registration is realized by spatial feature points. For the problem that the deformation monitoring points are difficult to select, the quantity is large, and the workload is large, a deflection curve based on the algorithm is proposed. The method realizes deformation monitoring without monitoring points. At the same time, the finite element simulation is combined with the deformation monitoring of 3D laser scanning technology to evaluate the structural safety state through stress change, which has important guiding significance for structural health monitoring.