Period-doubling bifurcation has been frequently observed in the numerical simulations of atmospheric dielectric barrier discharges and it also has been partly confirmed in our previous experiments. In this letter, we report inverse period-doubling bifurcation in an atmospheric helium dielectric barrier discharge. Experiments are carried out under parallel electrode configuration. By only increasing the amplitude of the applied voltage, we observe that the discharge successively experiences chaos, period-four, period-two and period-one. As well as the experimental waveforms, the fast Fourier transform of the discharge current is given to qualitatively demonstrate the state of the discharges. Although the observed bifurcation behavior is seemingly similar to the wellknown period-doubling bifurcation, it is essentially a different type of bifurcation behavior which has never been experimentally reported in the atmospheric dielectric barrier discharges. As a strongly nonlinear temporal-spatial system, the atmospheric dielectric barrier discharge could present far more complex behaviors under certain conditions than we thought. Further studies are still required to better understand the underlying mechanism of these complex behaviors.