With the progress of building materials and building technology, the span of bridges is becoming larger and larger. This paper briefly introduces the incremental launching construction technology of a bridge and the incremental launching construction technology of pontoon fulcrum conversion, makes an instance analysis on a large-span steel arch bridge that adopted the incremental launching technology of pontoon fulcrum conversion in Shaoyang, Hunan, China, and makes a simulation calculation on the construction process using Midas civil software. The construction process was monitored using stress sensors and total station. The results showed that the simulation results of the stress and deformation changes of the steel arch bridge in the construction process were close to the actual monitoring data, and the variation trend was basically the same. The finite element model effectively simulated the stress and deformation changes of the steel arch bridge in incremental launching. With the progress of construction conditions, the maximum stress and deformation degree of the arch rib increased first and then decreased, the maximum stress and deformation degree of the main longitudinal beam showed an increase tendency, the maximum stress of the front guide beam increased first and then decreased, and the deformation degree gradually decreased.