It is difficult to the quantitatively evaluate the effects of human activities and natural factors on the variation of river runoff and sediment in hydrology and water resources science. Based on the dates of precipitation, runoff and amounts of water and soil conservation measures during 19962012 from three branches in the middle reaches of the Yellow River,analyzed long-term response characteristics of river runoff in the context of climate change and human activities using vector autoregression (VAR) model. Results showed that response of runoff usually lagged behind precipitation and soil and water conservation measures carried out,runoff changes usually turned prominent on the second year and beyond the second year. Influences of different kinds of soil and water conservation measures on runoff was not static in 15 lag periods. After soil and water conservation measures were carried out,the longer times,the less the variation of runoff. Forestland was the dominant factors in decreasing the runoff during the year of 1996 - 2012. By use of variance decomposition, contribution degree of each factors followed as the order: grassland < protected-land < forestland < terraced field < dam-field < precipitation,and that amounts of soil and water conservation measures accounted for above 60% reductions of annual runoff in a long-term,as time goes on,the contribution level will be increase. The decrease of runoff resulted from the continuous increase of soil and water conservation measures.