Contribution of large-scale vortex and fine-scale turbulent structure in separated flow control by DBD plasma actuator are investigated using computational results of large-eddy simulation and two-dimensional simulation. The Reynolds number based on chord length is 63, 000 and 10, 000. The angle of attack is 14 deg. for Re=63, 000 and 10 deg. for Re=10, 000. The DBD plasma actuator is set at the 5% chord length from the leading edge of NACA0015 airfoil and operated in burst mode. At the Re=63, 000, the spanwise vortex breaks down into the turbulent small-scale vortices. However, the spanwise vortices in the two-dimensional simulation maintained their structure while they convect to the downstream. Comparing the lift-to-drag ratio, similar values are obtained in the F+ = 1 and F+ = 6 case, while the F+ = 6 case shows higher than the F+ = 1 case in the large-eddy simulation. These results indicate that the effect of the small-scale vortices are important to reduce the recirculation region of the separated flow and improve the aerodynamic performance in the F+ = 6 case. On the other hand, at the Re=10, 000, similar trend of the flow fields are obtained from the large-eddy simulation and the two-dimensional simulation. This implies that the effect of the small-scale vortices to the separation control is small at this Reynolds number.