According to practical requirements of water transfer in west route of the South-to-North Water Diversion Project, an idea of multi-method comprehensive determination of ecological water demand process in water source area was proposed based on method comparison, target adjustment, feasibility verification, and the ecological base flow in dry and non-dry periods, sensitive ecological water demand, and annual ecological water volume targets at 10 dam site sections were formulated. The results indicate that the ecological base flow at dam site sections in the water source area accounts for approximately 20% of the multi-year average flow in dry period, increasing to about 40% in non-dry period. The period from March to June is critical for fish spawning, necessitating monthly pulse flow events lasting at least 10 days each, and the pulse flow accounts for 48% to 73% of the total multi-year average flow. The proportion of the average annual ecological water volume at dam site sections to the multi-year average runoff is approximately 70%, and the proportion varies from 68% to 78% during high-flow years, from 66% to 75% during moderately dry years, and from 61% to 70% during drought years. These findings comply with current control requirements in the Yangtze River Basin, demonstrating good practical feasibility.