The rugged terrain, complex landforms and uneven coverage distribution of radio waves in high-altitude mountainous areas bring great challenges to the reliable networking of mobile users, especially intelligent vehicle devices. This paper mainly studies the influence of terrain on the propagation loss of vehicle to infrastructure (V2I) network in this environment, and predicts the loss of radio waves propagating from transmitter to receiver. By establishing the V2I network system model in the high altitude mountainous area, using digital elevation model (DEM) database and triangulated irregular network (TIN) to finely divide the surface, and combining with the basic propagation loss model in this environment, the simulation analysis is carried out. The simulation results show that the terrain has a great influence on the radio waves, especially the blocking of the mountain easily affects the wireless network communication in this area. In this paper, the prediction of the propagation loss of V2I network caused by the terrain in the high-altitude mountainous region can be used for the future implementation of 5G intelligent vehicle-infrastructure cooperation system and the construction of Cellular vehicle-to-everything (C-V2X) communication network in this region.