Abstract:Across Taihu Lake watershed in China, landscape change associated with urbanization, particularly urban sprawl, has been significant during the last half century and is expected to continue through the next decades. We organized the study around key questions: how did urban land expand in the study area? What is the impact of urban spatial change on ecological land quantity and pattern？We adopted some spatial metrics by use of ArcMap and FragStat to answer these questions: applying Intersect and Buffer functions of ArcMap to analyze spatial relationships between urban land and road corridor; using fractal dimension (FD) based on FragStat to measure urban expansion form; getting the contribution rate to ecological land growth (CRG) and contribution rate to ecological land reduction (CRR) by urban land according to the transition matrix between ecological and urban land to describe impacts of urban land sprawl on ecological land quantity; developing Insulation degree (ID) to measure impacts of urban land sprawl on ecological land pattern. The major results are: (1) Urban land sprawled obviously along transportation corridors. Mean percentages of added urban land in buffer belts (R1, R2, and R3) are 88.24%, 90.23% and 94.68%, respectively. (2) The distribution curve of urban land expansion form (FD) showed a ring and “U” shape. Towns with MFD>=1.5 is around one wing Ua where 73.68% of urban nodes UR3 are lied, and towns with 1.250, and the highest value of MID was high to 89.32.