Dielectric barrier discharge (DBD) plasma actuators were used for the active control of flow separation on a curved wall simulated suction surface of a gas turbine blade at three different mainstream velocities, U_MS = 2.2 m/s, 4.1 m/s, and 6.3 m/s. Owing to the change in mainstream velocity, the Reynolds number was varied as Re = 1.7 × 10⁴, 3.1 × 10⁴, and 4.7 × 10⁴, respectively. Particle image velocimetry system was used to obtain two-dimensional velocity field measurements. The amplitude of input voltage for the plasma actuator was changed from ±2.0 kV to ±4.0 kV. At the lower mainstream velocity, U_MS = 2.2 m/s (Re = 1.7 × 10⁴), the separated flow induced on a curved wall was consider-ably reduced by the flow control using the DBD plasma actuator. Moreover, the effect of flow control by the plasma actuator was gradually reduced at the higher mainstream velocities, U_MS = 4.1 m/s and 6.3 m/s (Re = 3.1 × 10⁴ and 4.7 × 10⁴, respectively). The flow control effect was improved by changing the position of the plasma actuator. When the plasma actuator was positioned immediately before the separation point, it exhibited better flow control effects than when positioned immediately behind the separation point.