Field measurement of airflow at 2 m high over semi-fixed longitudinal dune surface was made in the southern part of Gurbantunggut Desert in order to understand the various change of flow velocity over this dune type.It was found that wind velocity varied over the dune surface and the changes associated with primary wind magnitude and direction and slope morphology.The airflow velocity increased up the stoss slope and decreased down the lee slope.A very strong linear relationship exists between amplification of wind velocity and primary wind speed.The large the incidence angle between primary wind direction and dune is,the greater the extent of wind velocity tended to be.The landform has a significant effect on the airflow as well.There is a slow change of wind velocity down the gentle slope but a great change when the slope is steep.