From 2004 to 2010, by united operation of reservoir groups before flood season, 7times of man-made density current had been shaped in Yellow River, the sediment delivery rate of Xiaolangdi Reservoir varied considerably, and the effect of sediment ejection is not ideal. This paper analyzes the influence of different factor on density current sediment ejection, such as incoming water and sediment, suspended sediment content, variation of water and sand in Hedi station, Sanmenxia Reservoir operation, and incoming water composition of Tongguan and so on. The results showe that: ①Incoming water and sediment plays a crucial role in shaping density current. ② During the period of density current, if the content of fine sediment is more higher, the sediment delivery ratio will become more bigger. With the increase of sediment delivery ratio of total sand, the sediment delivery ratio of group sediment also increases, and the increase of fine sediment is the most. ③ During the period of large discharge release of clear water from Sanmenxia Reservoir, scouring happen in the river reach upstream Hedi station; during the period of free sediment release, deposition and scour can perhaps happen in the river reach upstream Hedi station. In actual operation, the hyper-concentrated flow discharged from Sanmenxia Reservoir can be properly controlled to reduce deposition of river reach upstream Hedi and improve the effect of density current.