Abstract: Based on data from the Huanghe (Yellow) River, the sediment storing-releasing process in an alluvial channel has been studied. The results show that in a hydrological year, sediment storing occurs during the high-flow season and sediment releasing occurs in the low-flow season. The amount of sediment storage in the high-flow season exceeds that of sediment release in the low-flow season, and net storage is positive for the whole year. Some thresholds for the critical storing-releasing state of the channel have been identified. When the event average suspended sediment concentration is smaller than 31.68 kg/m³, or the event sediment amount supplied from the "coarse sediment producing area" is smaller than 45.35?10⁶ t, the channel would change from a state of sediment storing to sediment releasing. When the ratio of event water amount supplied from the "clear water source area" in the upper Huanghe River to the event total flood water is high than 0.70, the channel would also change from a state of sediment storing to sediment releasing. The event sediment delivery ratio (R_sd) of lower Huanghe River channel increased with the event mean water discharge (Q_mean) to a peak, at which Q_mean=4 000 m³/s, roughly equaling the bankfull discharge, and then R_sd decreased. This indicates that channel sediment storing is the least at bankfull discharges, and when Q_mean is larger or smaller that bankfull, sediment storing increased.