This study analyzed the wind-sand flow field of a highway roadbed to reveal the formation mechanism of pavement sand damage, which provides a theoretical basis for the prevention and control of sand damage on a road surface in a shifting dune area. The study area was Highway 303 in Zhongzaohuo, Qinghai Province, China, which was selected based on computation fluid dynamic numerical simulation. The numerical simulation results showed that when the airflow passes through the shifting dune and the roadbed, the airflow velocity is divided into zones. In the presence of a flowing dune, the range of the deceleration zone around the subgrade increased significantly, while the subgrade slope and the leeward slope were all in the low speed airflow zone. On the top of the sand dunes, the air velocity increased sharply and was affected by the shape of the obstacles, which caused the wind speed to change from the “Ω” type to “M” type distribution. When the original sand control system on the dune surface is not maintained and updated, sand grains accumulate in large quantities near the dune. In this manner, the dunes will slowly move in the main wind direction and become the sand source, thus burying the roadbed and causing sand damage. The numerical simulation results are consistent with the actual results obtained, which indicates the accuracy of the numerical simulation. For the prevention and control of road sand damage in the shifting dune area, the local geomorphologic form and the law of wind-sand flow movement should be investigated in detail. Checking and maintaining the original protection system regularly, and cleaning up the accumulated sand in a timely manner will prevent the wind-sand flow from supplying the sand source, and will prevent the sand itself from becoming the sand source.