Abstract: The accumulative deformation characteristics of soils are crucial for designing subgrade structures and maintaining the long-term dynamic stability of the subgrade. Due to the effects of freeze-thaw cycles in saline soil regions, liquid soluble salt solutions and solid crystalline salt particles undergo crystallization-dissolution and salt accumulation-desalination. These processes not only cause changes in soil structure and physical properties but also influence the dynamic properties of saline soil. Based on freeze-thaw cycle tests, dynamic triaxial tests with different dynamic stress levels were conducted to study the accumulative deformation characteristics of saline soils in the Lop Nur region under the dynamic load of railway. Criteria for plastic behavior and a prediction model of accumulated plastic strain were established. The results show that accumulative deformation increases with both the number of freeze-thaw cycles and the increase in dynamic stress level. Under the simulated dynamic load of railway, the accumulative deformation behavior of saline soil in the study area is mainly characterized by plastic shakedown and plastic creep phases. The relationship between the accumulated plastic strain rate of saline soil and the number of loading cycles can be well described by a power function. Based on this, an accumulated plastic strain model considering freeze-thaw cycles and dynamic stress is proposed. These research results can provide references for settlement prediction and dynamic stability evaluation of saline soil subgrades under freeze-thaw effects and cyclic dynamic loads.