We estimated the minimum ecological influx in the lower Tarim River via the wetted perimeter method using the curvature technique. Calculations were based on river geomorphology data during the fifth and sixth ecological water conveyances. Results showed that the minimum ecological influx of the three control sections of the river (Yinsu, Alagan, and Yiganbjima) were 2.85, 3.76, and 1.76 m3/s, which accounted for 9.7%, 14%, and 6.9% of the multi-year average annual discharges, respectively. Except for the dry season, annual ecological water demand of the river was 0.79 × 108 m3, excluding evaporation and leakage. Multiple methods were used to prove the rationality of the results. It is by using the Tennant method that the percentage of minimum ecological influx accounting for multi-year average flux varied from 6.9% to 14% (average 10.2%), which is considered normal for the maintenance of river habitat. It is by using the R2Cross method that the minimum ecological influx of the lower Tarim River was 2.935 m3/s. These calculation results mirror the actual situation and serve as the base of water-source distribution in lower Tarim River. Further research is required to validate and adjust the results according to long-term hydrographic observations. Copyright © 2012 John Wiley & Sons, Ltd.