The method of indicators of hydrologic alteration and range of variability approach(IHA/RVA)was used to quantitatively evaluate the change degree of hydrological parameters at representative stations in the mainstream of the Tarim River and ecological effects caused by the operation of reservoirs in the upper reaches of the Tarim River. The results show that the operation of the reservoirs caused a significant change of the eco-hydrological regime of the Tarim River, and the change degrees were all higher than 60%. Significant changes occurred on the average flows in March and June, the annual 1-day and 3-day minimum discharges, the annual 30-day and 90-day maximum discharges, the number of low pulses, and the number of reversals. Reservoir operation significantly affected the ecosystem around the Tarim River. It is urgent to regulate the discharge of the river, in order to achieve the harmonious development of regional economy and ecological environmental protection.