Abstract: The wind erosion sand grains of the cultivated land in the typical agro-pastoral transitional zone in the northern foot of Yinshan Mountain in Inner Mongolia were collected with SC-I sand harvester. The collected sand grains were analyzed to calculate the essential parameters for dynamics of sand grains. In the view of acting forces of single soil grain in airflow and the data measured in fields, four-fifth Runge-Kutta-Felhber (RKF) algorithm was adopted to study the trajectories and movement characteristics of sand grains with different force conditions. The results showed that the floating state happened easier with the decreasing of the sand grain diameter. The rotational angular velocity (ω) and vertical initial lift-off velocity of sand grain (v0) were required to be higher when the sand grain diameter increased. Therefore, the sand grains with the diameter less than 0.075 mm were the main grains suspended in the air, and the general double-factor prediction model of maximum height (Hm) of sand grain was constructed in terms of the diameter (D) and vertical initial lift-off velocity (v0) of wind erosion sand grain. By studying the wind erosion characteristics in the region, some foundations are provided for the further research on the wind erosion dynamics characters and soil desertification prevention measures.