Two-dimensional numerical simulations of the discharge process in a dielectric-barrier-discharge (DBD) plasma actuator were carried out toward the detailed understanding of the electrohydrodynamic (EHD) force characteristics and proposal of the suitable voltage input in view of the EHD force production. In this study, the inuence of the voltage amplitude on the discharge regime and EHD force is investigated when a triangle voltage waveform is applied. The streamer discharges are obtained with high amplitude in the positive-going phase in a voltage cycle, whereas no streamer propagation is observed with low amplitude. In the negative-going phase, the frequency of the repetitive current pulses decreases with decreasing the amplitude because the voltage slope decreases with the same voltage frequency. The charge on the dielectric surface has a quite important role in the discharge inception voltage; the discharge is ignited in the negative-going phase even though the applied voltage is positive. The time-averaged EHD force increases with increasing the voltage amplitude and can be divided into two-power law regions. The increment rate of the EHD force changes sharply when the discharge regime transits to the streamer discharge. A wall jet induced by the DBD plasma actuator in quiescent air is reproduced by using the EHD force distribution obtained from the discharge simulation, which shows qualitatively agreement with experimental result.