Based on gray relational analysis, the driving forces of urban expansion in Wuhan City was studied using statistical data during 2003-2012. Result showed that the improvement of traffic conditions, the growth of people's income and population were the main driving forces of construction land expansion in Wuhan City during the past decade. The driving forces showed certain time scale dependence:the two factors, traffic and population, showed more significant effect on promoting rapid expansion in short-term, while the effect of income was mainly reflected in long-term. The increase of macro economy and the adjustment of industrial structure improved the efficiency and intensive level of land use.