Abstract: Taking the Huangle Hydropower Station in the Huangshui River Basin as an example, the suitable ecological flow and ecological base flow of the river channel were calculated based on the natural water flow paradigm. With ecological flow as the main constraint, a synergistic optimization model of ecological protection and power generation for small hydropower stations of runoff diversion type was established, and the Pareto solution of water diversion power generation flow was obtained using NSGA-Ⅱ. The research has high instructive values for the ecological dispatch and operation management of runoff diversion type small hydropower stations. The results show that the abrupt change point of the annual runoff time series of Xining Hydrological Station is 2000 diagnosed by sliding t test, and the average natural runoff is 41.3 m~3/s from 1956 to 2000 according to the calculation. The distribution ratios of the suitable ecological flow in the low-flow period, level water period and high-flow period are 0.60, 0.41 and 0.42, respectively, and the ecological flow has reached the “excellent” standard. The “general” standard of Tennant method is recommended for the determination of the ecological base flow, according to which the ecological base flow is 4.13 m~3/s in non-flood season and 12.4 m~3/s in flood season. The annual power generation is 6.342 9×10~6 kW·h calculated by the ecological protection-power generation synergistic optimization model under the condition of multi-year average inflow, and the discharge flow of the hydropower station hub meets the ecological flow requirements of the water-reducing reaches. The Huangle Hydropower Station has equivalently reduced carbon dioxide emissions by 6, 323.9 tons under multi-year average flow conditions, the ecological benefit of emission reduction is 1.884 5×10~6 yuan, and the economic benefit of power generation is 1.344 7×10~6 yuan.