The 1972, cutoff water flow in the lower course of the Huanghe river worsened day by day. In the 1970s, the time of the cut-off water flow was 8.6 days annually, in the 1980s, it was 10.5 days, in the first 6 years of the 1990s, it was 89.6 days, in 1977, it was 226 days, when the cut-off water flow was 704km. Large increase in the use of water volume for industry and agriculture in the Huanghe River basin was external cause for the cut-off water flow; However, deficient of water resources was basic reason or internal cause. In 1949, use of water for industry and agriculture is only 74 ×108 m3/a, but it increase to 300×108 m3/a in 1990s. The utilization ratio of the Huanghe River water resources is 60%, the first level in the world. 300×108 m3/a only account for 3.3% annual runoff in the Yantze River and 8.6% in the Pearl River but it is more than 1/2 of annual runoff in the Huanghe River. If preventive measures are not adopted, the situation of the cut-off water flow will worsen and be grimmer day by day. The situation of the cut-off water flow can be remedied by unified manage, proper allocate and conservation of the water resource in all basin, and adoption various cut-down water measures. However, allocation of water from the south to the north is the best method to resolve the problem of cut-off water flow and thus increase runoff o the sea and strengthen the construction of the ecological environment and enable sustainable use of the marine environment and resources in the Huanghe River estuary and adjacent sea area.