Relying on the reconstruction project of Tibet Yangda Highway, an important national project of the One Belt and One Road, the mechanical characteristics of freezing and thawing of culverts in plateau permafrost regions are studied. Using Midas GTS NX finite element software to establish mechanical models of steel bellows culverts and underwater antifreeze reinforced concrete pipe culverts under four working conditions, and analyze the changes in soil internal forces before and after freezing and thawing cycles of two commonly used culvert pipe materials in plateau areas. The internal force and displacement changes of pipe culvert and other structural layers, and the internal force changes of the two-way HDPE high-density polyethylene geogrid. The research results show that the plastic zone of pipe culverts of both materials increases after freezing and thawing cycles, but the use of underwater antifreeze reinforced concrete pipes has a better coordinated deformation ability; the midpoint and ends of steel bellows culverts after freezing and thawing cycles The principal stress, shear stress change rate, and displacement of different subgrade slope measuring points are all smaller than underwater antifreeze reinforced concrete pipe culvert, which is more suitable for use in plateau cold areas; two-way HDPE high-density polyethylene geogrid can effectively reduce the road surface Uneven deformation of the structural layer; the comparison and analysis of the theoretical calculation value of the modeling and the detection data of the construction site verify the correctness of the method in this paper.