Abstract: This study aims at the characteristics of ice regime and its influencing factors in the river reach upstream of the Wanjiazhai reservoir to provide a basis for ice control and scheduling. We have examined and compared the ice regime in natural river condition and the new ice regime under operation of the reservoir, using the field measurements during 1987-2015, and analyzed ice regime factors: river morphology, meteorological condition, reservoir operation, and hydraulic factors. The results show that in the reach upstream of the reservoir, the ice regime was featured with a freeze-up process advancing downstream to upstream and a freeze-up type either juxtaposed, packed, or mixed in different section along the river. Ice break-up occurred in the packed freeze-up section and its upstream later than in its upstream; in the upstream section it started at the downstream and was advancing upstream. The whole reach took forms of thermal, mechanical, and semi-violent break-up. Since 1998 when the reservoir started to operate, the ice regime in its upstream river has changed greatly due to changes in riverbed form, air temperature, reservoir control, and hydraulic factors. Major changes were observed in three aspects: ice-run date and freeze-up date were delayed while break-up date was shifted earlier; seldom-freeze-up reaches were turned to stable freeze-up with longer freeze-up river sections; in freezing period, water level was rising and the occurrences of ice jam and ice dam were increased. The comprehensive analysis of ice regime in this study would help ice control decision for the Yellow reach upstream of the Wanjiazhai reservoir.