The discharge characteristics and temporal nonlinear behaviors of the atmospheric pressure coaxial electrode dielectric barrier discharges are studied by using a one-dimensional fluid model.It is shown that the discharge is always asymmetrical between the positive pulses and negative pulses.The gas gap severely affects this asymmetry.But it is hard to acquire a symmetrical discharge by changing the gas gap.This asymmetry is proportional to the asymmetric extent of electrode structure,namely the ratio of the outer electrode radius to the inner electrode radius.When this ratio is close to unity,a symmetrical discharge can be obtained.With the increase of frequency,the discharge can exhibit a series of nonlinear behaviors such as period-doubling bifurcation,secondary bifurcation and chaotic phenomena.In the period-doubling bifurcation sequence the period-n discharge becomes more and more unstable with the increase of n.The period-doubling bifurcation can also be obtained by altering the discharge gas gap.The mechanisms of two bifurcations are further studied.It is found that the residual quasineutral plasma from the previous discharges and corresponding electric field distribution can weaken the subsequent discharge,and leads to the occurrence of bifurcation.