Based on remote sensing images and GIS data, we applied spatial expansion method and geographically weighted logistic regression (GWLR) model to explore the driving forces of urban expansion in Jiangning District of Nanjing from 1999 to 2010. Special attention was paid to spatial heterogeneity of key factors behind urban growth. The results show that 1) the spatial expansion method and GWLR model explained 57%, 64% of the urban land change of the area under study over the period from 1999 to 2010. The two methods both enhanced explanatory power in comparison with the global regression model (51%) and confirmed the spatially non-stationary process of urban growth; 2) compared with spatial expansion method, GWLR model is more effective in characterizing the spatial variations of the underlying factors of urban growth and therefore, it can be well applied to explore the mechanisms of urban expansion and policy making, as evidenced in this research; and 3) among various explanatory factors, DIS2INDU, DIS2ORD (proximity variables), DIS2CENT (neighborhood variables) and DENURBAN (policy variables) are the key driving factors of urban expansion in the area under investigation.