Abstract: Lantsang bridge and tunnel crossing project for the Myanmar-China Oil and Gas Pipeline consists of one bridge and two tunnels. Because of the serious landform relief and complex meteorological and geological conditions at crossing location, and the reservoir bank rebuilding as a result of water storage for a new hydropower station downstream, the project design is extremely difficult. After survey and comparison of multiple programs, the following design philosophy is determined, that is, line selection according to geological conditions, tunnel excavation based on bridge, and coexistence of bridge and tunnel. Moreover, all available site conditions will be considered to make the pipeline pass the Lantsang successfully. This paper presents seven difficulties of the design, and describes the process and approach of the selection of crossing section and the design of crossing project. The results can provide a reference to the design of large-diameter pipelines crossing similar or specific areas.