The technique used to control the airflow is based on the electro-hydrodynamic actuator which is also called plasma actuator. This actuator ensures the airflow control thanks to the electric wind created by the electrical corona discharge. This ionic wind is developed at the profile surface tangential to the initial free airflow so that it has a significant effect on the boundary layer flow. The studied profile was a NACA4412 airfoil. The electro-hydrodynamic actuator was placed at the surface of the NACA profile. The PIV visualizations made at angle of attack of 18o show an earlier flow reattachment to the profile surface when the plasma actuator is active. PIV measurements confirm that downstream of the actuator, when the discharge is ON, the wall velocity gradient is increased as illustrated by the velocity profiles taken at several positions on the NACA4412 wall. Then the plasma actuator can decrease the boundary layer thickness.