A parametric analysis were performed on a dielectric-barrier-discharge (DBD) plasma actuator to investigate the relationship between the inducedvelocity/power-consumption and the signal wave, voltage, frequency and electrode gap, respectively. Using the particle image velocimetry (PIV) and flow visualization technique, the starting vortices induced by the plasma actuator were observed in the quiescent air, including the downstream primary vortex which is relative to the exposed electrode, the upstream opposite vortex and the secondary vorticity associated with the primary vortex. The development of the primary vortex and the opposite vortex was studied, and the mechanism of the induced starting vortices was discussed by comparing the flow visualization and PIV results with the discharge current wave.