Abstract: A method was proposed to assess dynamically the ecological sustainability of the economic system in the Nanfen open pit mine empirically, based on the ecological footprint in the period from 1995 to 2007. The results showed that all the annual ecological footprint indices were smaller than -100% in the period, and the ecological deficits per RMB 10000 industrial output fluctuated with an amplitude of 0.01 hm² · (RMB 10000)^-1, with the average growth rate of annual industrial output values up to 12.79%. Although the average coefficient of elasticity of ecological footprints corresponding to economic development in the period was 1.27, the average growth rate of ecological bearing capacity was only 2.85%. A conclusion is therefore drawn that the future development of the economic system in the mine may be restricted by the limited supply of local ecological resources, thus coming into an unsustainable state.