Abstract: The Qarhan-Golmud Highway of Qinghai Province is located in cold region of Qinghai-Tibet Plateau and salt lake region. The mechanical properties of saline soils varly with moisture and climate, which will influence the project construction. The gravel piles formed by the dynamic compaction replacement are applied in composite foundation of saline soils, and field tests are carried out in this region. It provides methods for determining the coefficients of the capacity and deformation modulus of composite foundation with the gravel piles formed by the dynamic compaction replacement. The calculated values are analyzed, and they meet the met design requirements. At the same time, the strength and working mechanism of pile-soil and settlement reduction of the composite foundation are analyzed after reinforcement. The reinforcement case of dynamic compaction replacement has good reinforcement effects in saline soils of salt lake region, which helps the migration of water and salt and reduces foundation settlement in saline soils.