In the construction of super large bridges, trestle has been widely used as an important water passage, so the safe and reliable design of trestle is an important link for the smooth implementation of bridge projects. Taking the construction of the foundation and pier columns of Pier 5 of the Bar River Bridge as the engineering background, in response to the significant changes in the water level of the Ba River in the bridge site area, in order to ensure the construction progress of the main pier before the next flood season, a combination of high and low steel trestle bridge scheme was adopted, and utilized the “BIM(building information modeling)+digital simulation analysis” technology for simulation and structural analysis, the flood level heights of each stage were obtained through GIS （geographic information system） to determine the height of the trestle erection. Subsequently, MIDAS software was used to verify the various components of the high and low level composite steel trestle structure. The results indicate that the design of the high and low level composite steel trestle structure is reasonable, and the overall stability and safety meet the requirements of use. The successful application of high and low level composite steel trestle bridges provides certain reference and reference for the construction of similar projects.