The Yellow River estuary has the most extensive coastal wetland ecosystem in the Chinese warm temperate zone, with the most significantly natural attributes and completely ecological system structure. As a typical representative of new-born estuarine wetlands in the world, the Yellow River estuary wetland provides a variety of ecosystem functions, including biodiversity maintenance, environmental purification, groundwater recharge, soil conservation, etc. Freshwater flow affect the structure and function of wetland through changing estuarine landform, hydrology, habitat and ecological processes. Therefore, freshwater plays a decisive role in establishing and maintaining the health and evolution process of estuarine wetland ecosystem. However, the water resources in the city is less than 15 % of China"s per capita water resources, so the contradiction of water resources in the Yellow River estuary wetland is prominent. What’s more, due to the complex interface of river-sea-land intersection, the estuarine wetland ecosystem is very fragile, so meeting the ecological water requirement of wetlands is the key to maintaining ecosystem health. However, the previous ecological water requirement estimation of the Yellow River estuary wetlands lack a systematic comprehensive perspective and have the problem of coarser time scale. Based on three objectives of maintaining wetland area, protecting biodiversity and stabilizing ecosystem function and process, this study constructed a wetland ecological water requirement index system containing five indicators, and estimated wetland ecological water requirement at three levels and three periods. In addition, we judged the ecological water requirements of the Yellow River estuary wetland in extreme wet years and dry years in the past 20 years. Finally, this study concluded that the maximum, suitable and minimum water requirement of the Yellow River estuary wetlands throughout the year was 13.33×108 m3 ,22.33×108 m3 and 35.31×108 m3, respectively. The suitable ecological water requirement from April to June, July to October and November to March was 6.76×108 m3, 10.10×108 m3, and 5.47×108 m3, respectively. In 2002, the appropriate ecological water requirement of the Yellow River estuary wetlands in three periods was 4.17, 1.09 and 2.39 times of the runoff, respectively, showing an extreme water shortage; the appropriate ecological baseflow ratios for the corresponding periods in 2019 were 25.67 %, 15.77 % and 37.01 %, of which the ecological water conditions in April to June and November to March were tighter and water replenishment should be carried out according to the actual situation. The results of the study are expected to provide quantitative support to ensure the wetland ecosystem health and scientific water management of the Yellow River estuary.