Abstract: A self-consistent fluid model was developed describing the spatiotemporal characteristics of parameters in the radio-frequency plasma sheath under DC bias without molecule collision, considering the effect of DC negative bias of electrode on ion motion. In the model, the thickness of the sheath was regarded as a function of time, and the relationship between the instantaneous sheath thickness and potential drop of sheath was established by an equivalent circuit model. Simulation results showed that the electrode presents a cyclically non-sinusoidal potential. The variation cycles of both sheath thickness and potential of electrode are the same in opposite trends, and they lag slightly behind radio-frequency cycle.