Abstract: It is the dominating engineering for Myanmar-China Oil and Gas Pipeline to make both oil and gas pipelines cross the Nujiang River on the same bridge. At the crossing section, the river is 270 m wide, the main span is 320 m and the end span is 60 m. The design concepts and methods of highway bridges are innovatively adopted in this project to address the difficulties like large single span, flexible structure, heavy bridge body, international river crossing and oil and gas pipelines crossing the river on the same bridge. The optimized load combination and the reasonable boundary conditions and resolution methods are obtained after analysis is performed on the mechanical characteristics of flexible structures by using three-dimensional model discrete processing technologies. When the model is analyzed, the full freedom coupling at the connecting position of the overhead and the main cable is taken as the constraint condition. In this paper, a reasonable design solution is proposed for static and dynamic simulation of crossing structures, and the prestressed anchorage design technology is, for the first time, applied in the industry of oil and gas pipelines, so that the anti-cracking and anchoring capacities of anchor structures are improved.