Abstract: ： The spatial characteristics of the ecosystem service value and accessibility to cities on three different levels（county-level cities,prefecture-level cities and mega cities） in Hunan Province are analysed. And three geographically weighted regression models are built to help revealing the impact of traffic accessibility on ecosystem service value. The results indicate that the negative impact of the accessibility of urban transport on the ecological service value from the urban agglomeration of Changsha-Zhuzhou-Xiangtan to the periphery is weakened and turned into a positive influence in the southwest of Hunan Province. The influence mechanism of the accessibility of the urban traffic on the ecological service value is similar to that of the county-level city,and the negative influence extends to the northwest along the railway. The accessibility to large cities has a positive impact on the ecological service value in whole Hunan Province,with the strongest in the east. Transport infrastructure construction and economic upgrading strategies should take the differences in the impacts of different levels of traffic accessibility on ecosystem services value in different regions into account to promote social and economic development while maintaining and developing the local ecological service value.

Key words: traffic accessibility, ecological service value, multiple administrative levels, geographically weighted regression