Based on the indicators of hydrological alteration method, the environmental flow indicators were determined and used to analyze the influence of water diversion in the Tarim irrigation area on the change of environmental flow at the Alaer-Xinquman cross-section in the mainstream of the Tarim River. The results show that the environmental flow components of the two hydrological stations changed to different extents after the irrigation with diverted water; the composition of environmental flow exhibited a trend of simplification; the flow events at all the hydrological stations were mainly low flow events; and the water diversion project had a significant effect on extremely low flow events, high pulse flow events, and large flood events. According to the relationship between the environmental flow indicators and the ecosystem, an optimal water resources scheduling scheme for the ecological environment was established, providing references for ecological management and water allocation in the Tarim River Basin.