Abstract: Since the 1970s,the water fluxes from the Yellow River into the sea have declined significantly.The formauve cause for this is dealt with in this study.Based on the data of precipitation,measured and "natural" runoff, water diversion and the areas of erosion control measures over the drainage,the relationship between the water fluxes and the influence of changing precipitation and human activities are studied.The Yellow River basin can be divided into some different water source areas.The change in precipitation over different runoff source areas has different effect on the water flux.The water diversion from the river forms a "lateral branch water cycle system",which increased intensively and resulted in significant decline in the water flux.Since the 1960s,the erosion control measures have been practiced over the drainage basin,leading to a decrease in the water flux into the sea.A multiple regression equation is established for estimating the change in water fluxes caused by the changes in precipitation,water diverlion and erosion control measures.