With the increasingly deep understanding of the significance of wetland,the evaluation of wetland ecosystem service attracts more and more attention.Before evaluating the ecosystem service,the wetland ecosystem functions must be ascertained rightly,and moreover,the wetland ecosystem functions are closely related to characteristics of surrounding environment.Based on summarizing status of wetland ecosystem service value,the wetland ecosystem functions were determined in combination with characteristics of the wetland and surrounding environment in bayou headwater wetland of the Mudan River named Haerbaling.The wetland ecosystem functions mainly include gas regulation,climate regulation,water conservation,waste treatment,and biodiversity conservation.Then the affects of environmental features on specific wetland ecosystem functions were discussed,the wetland ecosystem service value were calculated.Finally,the suggest in view of how to improve the research of wetland ecosystem functions were proposed.