The test and analysis were conducted on oat crop stubble coverage farmland by means of the movable wind tunnel. The result showed that aerodynamic roughness increased with the increasing of crop stubble coverage width under the given velocities. The field surface velocity of windward reduced to less than that of leeward. The field surface aerodynamic roughness showed an extreme value when crop stubble coverage width reached to 5 m. Its increasing amplitude grew minuteness with increasing of crop stubble coverage width. Aerodynamic roughness increased with increasing of friction wind velocity and its increasing amplitude more than that of friction wind velocity. In conclusion, crop stubble coverage with reasonable width could reduce near surface shear stress. Compare with friction wind velocity, the effect of aerodynamic roughness on near surface shear stress was found to be more obvious. 