Antimony doped tin-oxide powders were prepared by controlled precipitation.Surface compositions were determined by X-ray photoelectron spectroscopy(XPS).The results indicate that enrichment of dopant at the surface of nanoparticles depends on total doping concentration and annealing temperature.Doped antimony shows the tendency to diffuse to surface when annealing at high temperatures.But same amount of Sb atoms are retained on the surface for powders annealing at different temperatures.The higher enrichment at higher temperature is caused by the decreasing of surface areas.Variation of the conductivities of SnO2 powders is also discussed.