Abstract: There exists two difficult issues in study of the trend and driving mechanism of urban expansion: (1) Maxed pixels of traditional landscape data reduce the accuracy of urban expansion trend research. (2) Collinearity of the driving factors affects the reliability of driving mechanism. To fix these problems, taking Nanjing City for example, the impervious surface was used to conduct weighted average barycenter analysis, linear direction mean analysis and standard deviation elliptic analysis to study the urban growth characteristics. Driving mechanism of urban growth was studied through combination analysis qualitatively and quantitatively (Partial least squares regression，PLS). Results showed that imperious surface in Nanjing showed multicentric and inconsonant expansion. Gravity center transfer distance of impervious surface increased over the three periods (2000 to 2005, 2005 to 2010, 2010 to 2017), which annual gravity center transfer distances were 303, 379 and 611m respectively. In general, the gravity center transferred 2 564 m to the direction that 259.12 degrees to the north clockwise. The exterior morphological characteristics of urban growth had obvious directivity, which the oblateness of the standard deviation elliptic of the impervious surface were all larger than 2.23 in 2000, 2005, 2010 and 2017. The external spatial characteristics of the administrative region, distribution of rivers and nature reserves, and the land use plan were the main factors that constrain and limit the direction of urban expansion. The number of employees in the secondary industry, population density, fixed assets investment in the tertiary industry, regional GDP, and per capita disposable income in urban and rural areas were the main factors that influenced the scale of urban expansion.