Abstract: To reveal the water balance effect and groundwater response of the water saving of agriculture in irrigated oasis and its impact on ecology,this research systematically studies the entire process of agricultural water saving,water balance effect,groundwater response and ecological impact.A water cycle model is constructed to simulate and analyze the water balance effect of Ningxia’s Yellow River irrigation oasis and groundwater system from 2008 to 2017,which reveals the changes in agricultural water saving irrigation and its accompanying changes on supply,use,consumption,drainage,and groundwater response,as well as their impact on ecology.The results show that the effectiveness of agricultural water saving is remarkable with a significant increase of 26% in irrigation water efficiency.The amount of water diverted from the Yellow River has decreased from 6.18 billion m³ to 4.78 billion m³,and the total infiltration supply has synchronously decreased.Among them,the leakage supply of rivers and canals has decreased from 2.847 billion m³ to 1.676 billion m³,which contributes 87% of the total reduction of infiltration supply reduction,and it is the fundamental reason for the decline in groundwater level.The area of the oasis with average groundwater depth of over 2.5m has increased by 2.1 times over the past decade,and continues to decline at a rate of 0.63m/10a.The average groundwater level in March and April has approached the critical value of groundwater levels for vegetation and lake ecological.The water replenishment effect of groundwater on natural vegetation is weakened,and the growth of some herbs and shrubs are affected.The groundwater recharge received by lakes has significantly decreased,which leads to the phenomenon of shrinkage or seasonal disappearance,and it only can be maintained by increasing artificial ecological replenishment to achieve a certain water surface area,but the degree of salinization is visible reduced.The vulnerability and degradation risk of oasis ecology are raising,and the ecological health is approaching a critical state.The impact and damage of excessive agricultural water saving on oasis ecology should be vigilant.