a one-dimensional self-consistent fluid model is employed to investigate the atmospheric-pressure argon dielectric-barrier discharge (dbd) excited by periodic gaussian voltage. with the driving frequency, voltage amplitude, and gas gap set at certain values, the temporal evolutions of discharge current density and gas voltage are obtained, together with the spatial distributions of electron and ion densities and electric field. simulation results indicate that there are two discharge modes: townsend and glow modes in the multi-current pulse discharge. a mutual transition between the townsend mode and glow one occurs during each half cycle of the applied gaussian voltage. the space charges in the gas gap and the surface charges on the dielectrics play a key role in the transition between the two discharge modes. additionally, a residual current peak is observed during the falling phase of each half cycle. this is resulted from the fact that amounts of space charges are trapped in the gas gap during the rising phase of the applied gaussian voltage. these findings contribute much to the design of plasma excitation source in applications, such as materials processing, pollution control, and biomedical sterilization.