Abstract: The study of ecological flow in a planned cascade system in the upper reaches of the Yellow River provides a foundation for developing ecological scheduling schemes. Gymnodiptychus pachycheilus was selected as the indicator species. Considering the habitat suitability of G. pachycheilus in terms of water velocity and depth, the HEC-RAS one-dimensional hydrodynamic model was used to simulate water depth and velocity distribution in the target scheduling reach under various flow and storage conditions. Based on the results of hydrodynamic simulation, CASiMiR-Fish habitat model was applied to assess habitat suitability for the target species within the ecological scheduling reach. Combining the changes in suitable habitat area of G. pachycheilus under different flow conditions and the distribution of the average daily flow from April to June of the downstream Tangnaihai water level section in the study area from 2002 to 2022, the results show that when the Yangqu Reservoir operates at the ecologically restricted water level of 2,710 m, the minimum discharge of 150 m³/s Bando is required during the main breeding season (April-June), with an appropriate ecological discharge range of 50—515 m³/s.