The evaluation of wetland ecosystem service lays the foundation to the wetland protection and exploitation. Evaluating the ecological service of all types of wetlands scientifically and reasonably is critical to improving the quality of ecological environment and securing the regional ecological security. In the middle reaches of the Yellow River, a typical sediment-laden river wetland- Sanmenxia Reservoir area Wetland, is chosen as the research target. Based on the systematic analysis its unique formation process and ecological services, the biological resources are formed, including the value of supply service, regulation service, support service, and cultural service. The value of wetland ecological services was calculated by market value, opportunity cost, shadow engineering and substitution cost methods. The results show that the total value of wetland ecosystem service is worth about 80.86 billion yuan, and the dominant ecological services are regulation service and support service with the economic value of 46.49% and 50.85% respectively. The evaluation results make people more directly understand the importance of wetland leading ecological service and provide scientific basis for the protection and management of wetland in Sanmenxia Reservoir area.