Abstract: Abstract：The researches of the spatial and temporal characteristics as well as driving mechanism of land expansion of Changsha-Zhuzhou-Xiangtan urban agglomeration, a typical agglomeration in Hunan province, is of great benefit to formulate the high-quality development planning of the urban agglomeration and land spatial development planning.A variety of analysis methods including Expansion Intensity Index, Landscape Expansion Index and SAR Probit model were used to study the characteristics of urban land expansion and driving mechanism. The results indicate: (1) The characteristics of urban land expansion varied when the urban agglomeration was at different stages. Its intensity was strengthened first and weakened later, forming a spatial pattern of “core-periphery” expansion. (2)The urban expansion process of urban agglomeration changed from diffusion to coalescence, which was consistent with the urban growth theory“diffusion-coalescence”.The growth type of leapfrogging was dominant during the urban land expansion period during 1995-2010;the growth type of edge-expansion,became the mainstream during 2010-2018.(3)With the factors like socio-economy, geography, accessibility and spillover effects, dual impacts were made in the process of urban land expansion.The socio-economy and spillover effects turned out to be the dominant factor controlling the urban land expansion. Furthermore, this paper puts forward a driving mechanism framework of land expansion, which was in the name of “four forces” model. These research findings will do good to the better understanding of urban land expansion of urban agglomerations and provide a scientific theory for the integration and construction of Changsha-Zhuzhou-Xiangtan urban agglomeration.